In memory of Tovia Kushnir

The late naturalist Tovia Kushnir's interest in biology and nature began as early as his childhood, and continued until his death in XNUMX. For the tremendous work of a naturalist of a rare breed, which includes breakthroughs in the field of botany, the animal world and nature

Uri Kushnir Galileo. The full article was published in the Galileo magazine, January 2011, and on the Hadaan website on 17/01/2011. Raised again on the occasion of Memorial Day for the fallen of the IDF.

Tovia Kushnir was born on October 12, 1923 to Shimon and Esther, who were among the pioneers of the settlement in the Jezreel Valley and the founders of the Kfar Yehezkel settlement. In his first "biological experiments" he started already as a tender child when he sowed and grew wheat and barley in the sand pile in his home and in the carrot fields he would cut rings, stick them in the sand and wait for them to grow. From the dawn of his childhood in the village his love for plants and animals was evident. At the age of 9, he was already engaged in growing cacti and cultivated an impressive collection while making connections with nurseries in the Jezreel Valley and cactus enthusiasts from Haifa.

He was drawn to the fields, wadis and ridges of the Gilboa much more than to the walls of the school, and with his childhood friend and fellow student Yigal Ptolemy (later the renowned physicist Prof. Yigal Ptolemy, recipient of the Israel Prize) he would go for walks, to collect butterflies during the flowering season and to collect wild species such as orchids, anemones, crocuses and irises . These were for the first botanical garden he established in the yard of his house. Besides the dog Zeva, to whom he became very affectionate, he tried to raise hedgehogs, turtles and chameleons, he would even bring food to a pair of falcons that built their nest between the barn's shingles. Shubach built a pair of abandoned chicks and even built a sukkah for himself to rest next to them. A special bond was formed between them and him, and when he walked in the center of the village, the birds would suddenly land on his head and shoulders and eat from his hands - to the astonishment of his friends and no less to their jealousy.

In 1939, after finishing his studies at the elementary school of Kfar Yehezkel, Tovia moved to study at the district school in Kibbutz Yegor. This period in his life was a formative and decisive period in the continuation of his development as a naturalist. He took it upon himself to set up a nature corner for the school and be responsible for it. Thus he began collecting and breeding about 12 species of snakes from the Land of Israel, two species of hummingbirds, amphibians such as the Land of Israel newt and a common salamander, as well as various species of fish. With the help of the definition of the plants of Eretz Yisrael (by A. Ig, M. Zahari, N. Finbron, first edition 1931) he expanded his knowledge of the flora of the Carmel and the Kishon and established a botanical garden of the plants of the Carmel, which also had trees; And when one hand held the plant bag, the other hand swung the net to hunt butterflies both for collection and breeding, and in addition to them also wild bees.
while we were a boy

In his quest for knowledge, Tovia made connections with the best naturalists who were in our country. As far as the subjects of reptiles, amphibians and fish and their breeding are concerned, he absorbed knowledge mainly from Dr. Heinrich Mendelssohn, whom he frequently visited with his many realities at the Yehoshua Margolin Biological Institute in Tel Aviv. On the topic of butterflies, he established contacts with Dr. Carl Reich and Dr. Alexander Barsh to learn with their help the theory of defining butterflies according to the structure of the arteries in their wings; He sat down with them and translated from German to Hebrew in order to create a definition board for him to identify them. With Yaakov Glimacher (later Prof. Galil) he established a relationship for the study of wild bees and Yaakov Flamoni - the director of the "Beit Gordon" nature museum in Dagenia - learned about arranging entomological collections, and would exchange species and details with him to complement each other.

However, the highlight of his connections was his acquaintance with Dr. Michael Zahari, who on his way to a tour of Carmel passed by Kibbutz Yagur and met the young Tovia. Zohari was impressed by his wealth of knowledge about the flora and fauna of the Carmel groves, among the rocks of the Gilboa, from the fields of the Jezreel Valley, from the Tabor and Givat HaMorah and from the waters of the Sahana. Michael Zahari would later write about Tobiah during this period: "His acquaintances while we were a boy, his eyes searched for disappearing valleys, accompanied flocks of birds, searched for their nests, penetrated and peered between the rocks, looked for orchids and irises and never got tired. In these eyes resided that curiosity that breeds perfect naturalists" (Michael Zahari: ("The Field" Nissan XNUMX, booklet XNUMX, volume XNUMX).

Tovia addressed his questions in botany with the plants that were the subject of his difficulties to the department of botany at the University of Jerusalem to Dr. Zahari and Ms. Naomi Finebron (who later became a professor in the department of botany, author of two of the four volumes of Ai's "Flora" and co-author of "Hamagdir le Tzemachi Wild In the land of Israel"). Indeed, even though he was only a boy, there were discoveries and innovations in his findings. The garlic he found in Carmel was a species new to science, even if Mrs. Finebron called it the garlic of the woods. Other species he found were not previously known for their distribution in Carmel but in the Judean or Galilee mountains such as the bluish bee and the large bee and the woodcutter.

When he was only a boy of about 16, Tobiah discovered the black lily in Wadi Maran in Carmel - his botanical discovery won at that time and evoked echoes. The search for the black lily interested the world of botany so much at the beginning of the 20th century, but even Aharon Aharenson was unable to find it until Noah Naftolsky discovered it in 1925 in Paki'in as a new species for the Land of Israel. Tovia felt with the onion he found at the experiment station in Rehovot El Noah Naftolsky - "the man of plants and flowers", his father Shimon's close friend - and Noah was very happy about his discovery, and only regretted that this discovery of Tovia would no longer be included in Prof. Otto Warburg's book, which was published ten years ago previous. After a week, Noah especially came to live and went up with Tovia to Carmel to see the plant in its habitat. Tobiah did not let Noah take out more than two onions. He was wary of the plant and worried about the hands that might destroy its rare representatives.

Tovia writes to Dr. Zohari during this period, that he takes it upon himself to make markings for him on maps of all the northern Carmel groves (the northern slope along the entire length from Haifa to Muharka, the watershed that goes through Hariva and Isfaya from Muharka to the foot of the Carmel) of the large trees in each grove and that he is also He remembers their concentration by heart, and at Zohari Tovia's request he even writes his comments on the vegetation of the Carmel and the Kishon.

In the meantime, Tovia wrote for the school newspaper "Yagorim" on the topics of flora and fauna, and he illustrated his notes with incredibly accurate hand-made drawings, which complemented his developed sense of observation. After Joshua Margolin and Mendelson "dragged" him to join their students on a tour of Carmel, they offered him to join them on a tour of the sick. Tovia joined the tour, which opened up a new world of flora and fauna to be discovered before him. After this tour, Weier wrote for the school newspaper a list full of knowledge about the flora and fauna in the Hula Valley as it was at the time.

He ended his list with the following words: "A big plan will surely come true after the war - drying huge wetlands. This will cure the scourge of fever and give enormous possibilities for agriculture to dozens of Jewish communities: but it will bring disaster to hundreds of plants, which due to the drying will disappear from the land altogether, to hundreds of birds, which will be homeless, as well as to species of animals and fish. America allocates huge areas of thousands of dunams for the preservation of one animal, and here in a patient not one animal, but many. And it is sad because no one will be found who will do anything for the sake of leaving wetlands for them. Today we witness the destruction of plants in Sharon, which took place several years ago. And today, after the swamps have dried up and the fields have been plowed, there is no longer a trace of them. It has already been said in one place: If the flora researcher in Vassier were to rise today from his grave, he would not know the land in which he collected so much. So now, and even more so after the drying of the richest and most beautiful place in the Hula swamps." (It will be published in "Yigorim", the district school newspaper in 1940.) This was written by a 16-year-old boy in 1940, about a decade and a half before the establishment of the Society for the Protection of Nature in the State of Israel.

Everything is interesting, everything is attractive

Dr. Zahari, who noticed Tovia's skills, suggested to Tovia and his parents that for the sake of his development for the future it would be good if he transferred to complete his high school studies at Beit HaKerem high school in Jerusalem, where the level of general education was higher. And Tovia did move to high school in Jerusalem and in the first year of his studies he even lived in Dr. Zohari's house. Tovia made up for the gap in his studies when he moved from the kibbutz to the city, and as Dr. Zahari testified: "His studies at school were a side effect for him. Even in the 'burning season' of the exams Tovia was immersed in his own - searching and investigating. Every day and its discovery, new habitats for the plants in Magadir, new forms, bees, mushrooms. Everything is interesting, everything is attractive.

"He used to walk to school between fields and mountains. Not to shorten the way, but because the walk is like a tour, and you can find something while walking to pick up from this and that. His military side knapsack was the bag for his books, but more than books it contained 'nature'. The backpack was full, this is a reality from everything that comes next."

During this period, Tovia continued on his free days from studies and vacations in his tours to the Judean desert, to Samaria, to Givat Hamora and Gilboa, to Tabor, to Wadi Bira and to El Hama. Of all of them, he came back with findings that were scientific innovations. In Sukkot 1943, Tobiah made an exploratory trip to Hermon and the Lebanon mountains, after his first trip in April 1942 was interrupted when he was arrested by British and French policemen, and tried for illegal border crossing. From this second trip, Tovia returned with the experiences of the magical landscape that were engraved in his soul until the end of his days and with a cargo of collections of about 400 species of plants. Decades later, with the conquest of Mount Hermon in the Six Day War and after Prof. Avi Shamida studied the flora of the mountain, Prof. Shamida assessed this collection contribution as one of the three milestones in the history of the study of the Hermon's flora, alongside the collections of Aharonson and Noah Naftolsky that preceded it.

Tovia completed his high school studies in Jerusalem, and in 1944 he went to a service year of agricultural work and weapons training in his village, Kfar Yehezkel. Any free time from work was used for research tours throughout the country. In this year, he discovered three types of crocus as new to the country: the yellowish crocus in Menara, a handsome crocus near Halhol in the Judean Mountains, and the Israeli crocus near Ramallah.

In 1945 he was accepted to study at the Hebrew University on Mount Scopus and turned out to be an outstanding student whose name precedes him in all biology subjects, but his tendency to devote himself to studying genetics and biochemistry and specializing in them increased. At the same time, he founded and established in the botanical garden of the university a botanical garden of all the onion and tuber plants of the Land of Israel, plants he collected from all over the country, planted and grew and conducted observations and experiments on them. For a special scientific interest and "closeness of soul" he had the irises of our country. To study their natural distribution and to collect them, his team traveled from the heights of Hermon to the deserts of the Negev and even in remote areas, where no Hebrew foot had set foot, and also for those whose entry was forbidden by the emergency laws of the British Mandate.

While studying at the university, Tovia formed special ties of scientific kinship and respect with teachers and researchers who later became professors: Elisheva Goldschmidt, Tsharna Reiss, Shaul Adler, M. Ashner and Aharon Kachelsky (later Katzir).
At the same time as his studies, Tovia began independent research work. Based on his cytogenetic work on the brown iris in his second year of studies, he published an article in the journal of the American Iris Society in which he refuted the association that was accepted in relation to this species, as belonging to the section Regelia; And this is in contrast to the morphological and phytosociological features pointed out by Tovia, which associate it with the Iris section (Oncocyclus).

Created ornamental plants by breeding species from wild plants

At the same time Tovia was engaged in research, under the guidance of Ms. Tsharna Reiss, in the phytopathology of the iris species of Israel for Septoria and Heterosporium diseases while discovering inter- and intra-sexual variation both in nature and in artificial infection in the laboratory in response to the diseases; This work of his was published in the journal Botany of the Land of Israel.

From all the iris species of the Land of Israel that he collected from the mountains and the desert, he created intersex cages which he raised in his part on Mount Scopus. These cages are intended for a complete program of genetic research on the relationships between them (biosystematics) and the inheritance of their colors. He published articles on selected groups of native plants such as orchids and other plants.

In the second year of his studies, he created a detailed proposal, which was the first of its kind in Israel, to create ornamental plants by breeding species from the wild plants of the Land of Israel. Based on his familiarity with the country's flora and his well-developed sense of beauty, he proposed a list of nearly 50 wild species, not only as a botanical list that includes their distribution in the country, but also with notes from his personal experience on the desired way of transferring them from nature to the ornamental garden and instructions for their cultivation and propagation. Fifty years after his downfall, about ten species from Tovia's proposals won commercial adoption (Prof. Avraham Halevi, in a personal conversation with me, 1998).

From his expertise both in pollinating insects such as butterflies and bees and in the plant world, he was then drawn in the 40s to the field of pollination biology. After he found caprifaga trees (with male flowers) near Tel Dan and near Maayan-Harod, he characterized their defects by their different flowers. I also characterized their wasps, both Blastophaga psenes and its secondary resident Philotripesis caricae, which Tovia found for the first time in Israel. These observations of his led to the writing of his article "On the origin of the fig and its fertilization problems". In his article, he raised profound genetic hypotheses about the formation of dioecy and the morphological difference that is so prominent between the edible fig and the caprifaga fig, despite the fact that they are two forms of one reproductive unit - of one species.

The transition to genetics

In 1947, in the third year of his studies, Tovia was drawn to cytogenetics as an important tool for deepening his knowledge of systematics and for clarifying the relationships between the various forms in nature and their formation - this is evolution.

From here he was completely absorbed in the study of Arabs (which was the first scientific work in the Land of Israel in the field of evolution), when the geographical uniqueness of the country as a bridge between Europe and Africa allows the discovery of evolutionary processes, caused by a sharp transition in the conditions of existence between the continents. In Europe, the garden wasp species Gryllotalpa gryllotalpa was known in three varieties, which differed chromosomally but not morphologically. In Africa there is another species, the African wasp G. africana, which differs from the European in both the structure of the chromosomes and the morphology. Tovia collected Arab populations from all over the country from the Arabah and the Dead Sea in the south to the Upper Galilee in the north. He made characterizations: cytogenetic in the chromosomes, ecological in the distribution and morphological in the vein of the upper wings and the structure of the head box.

Thus he found in Jerusalem another strain of the European species, which was new to the world of science and had a unique number of chromosomes, which is a transitional link between the European wasps and the African wasps. In Ein Khosev (measles) in the Arava he found the African wasp, while in Beit Arava on the Dead Sea coast he found a species with the same number of chromosomes as the African wasp, but morphologically different from it in most features. These two new species were defined as new species to science in 1998, fifty years after his death: the Tali and the Dead Sea.

From his findings in 1947, Tobiah concluded about evolutionary processes of speciation, which occurs within the genus Arzav today. He presented his opinion that in the differentiation of the species, the origin of the genetic material of the euchromatin - the gene coder - may be formed from the heterochromatin, which is not necessarily genetically inert and empty of genes, but instead contains genes in a dormant (latent) state. This, decades before studies in molecular biology showed that the replicative DNA (made up of repetitive nucleotide sequences), which was unknown in Tovia's time, has the potential for genetic expression in vitro, but is somewhat suppressed in the in vivo condition.

Tovia's work on cytogenetics and the evolution of neurons was published in its first part in the highly important scientific journal Nature, when he was still only a third-year university student, and the sequel came to publication when he was no longer living in the British genetics journal. The well-known editor of the journal, Prof. J.B.S. JBS Haldane - one of the greatest geneticists in the world of his time - to whom Tobiah aspired to reach a doctoral thesis, wrote a note in the margin of Tobiah's article: "The author of the article was killed in the last series of battles around Jerusalem - readers will know for sure the loss caused to biology in his death."

"The solution to the secret of life"

In this third year of studies, Tovia marked out for himself the direction of the scientific work he was aiming to reach: biochemical genetics (modern-day molecular biology), out of the recognition and appreciation that it is the one "that will deal with the focal point for all biological research - the secret of life - the study of gene activity and expression", as he put it. He began to prepare himself for working on these questions both in reading and theoretical knowledge and even in practice in the laboratory work.

In deciphering the secret of life in the activity of the genes and their expression, Tovia sought to direct himself in the future, to the right objects - "to the low single-celled creatures in which the action of the gene is revealed directly in elementary processes, which can be tested simply and directly." In the seminar he prepared on "Biochemical genetic problems in Telophyta" he wrote in a notebook that was left behind: "... It is possible that the plasma-gene thing (the gene product transferred to the cytoplasm) is not as rare as it is considered today, and is not limited only to sandalwood and yeast. It is possible that this is a general phenomenon in gene behavior and enzyme creation, but the technique used in research today is not capable of discovering these things." These are things written by a student in his third year of studies about a decade and a half before Nirenberg, Khorana and Ochoa (Nirenberg, Khorana, Ochoa) cracked the genetic code in 1966-1961.

Against this background, in the last weeks of his life, Tovia dealt with the biochemistry of changing the color of a mouse's fur. While breeding field mice in captivity, he observed the phenomenon of the appearance of a white spot on the chin of the brown mouse, a spot that spread in hybrids along the abdomen and limbs. Tovia believed that the phenomenon is due to certain primary and modifying genes, which can be isolated in pure lines. However, beyond that, due to the spread of the white color in the body of the mouse in a gradient from a certain center - this points to genes and inhibitors (super surim), which inhibit the development of the color and the activity of the enzymes associated with the creation of the hair color. Therefore, his assumption was that the point that will turn white most recently is the focus, from which the cascades of color spread, while the point where the white color first appeared - where the enzyme creating the black color recently arrived. And so Tovia began testing the enzyme tyrosinase, which converts tyrosine into melanin in the various tissue areas, in order to diagnose the link between the enzyme and the genetic change in melanin in the skin.

In the midst of his work, it was interrupted and not completed, after he left the walls of the university, he recruited himself and volunteered for the Palmach. In this direction, in which Tovia began, research work was carried out in the United States by researchers Korner and Pawelek (Korner & Pawelek) from Yale University 35 years after his death and was published in 1982 in the scientific journal Science.

"Lost in the world of science"

After the UN declaration in November 1947 on the partition of Israel, with the Arab attacks on the Jewish settlement in the country, Tovia volunteered for the XNUMXth battalion of the Palmach, in the company of his close friend from his youth and partner on many botanical tours - Yitzhak (Itzik) Halevi , who was now his commander. Tovia left his complete and half-complete studies, his many scientific plans and ideas behind, as he mobilized himself out of full recognition and identification with the order of the hour. Even if the man of the six had never come close to me, he wrote to our father a few days before his fall: "I know that the act I am doing today is the only one that might now give a Jewish boy a trace of satisfaction." He worked nights and days in the fifth grade, where he participated in the security of the convoys that broke out on the way to Jerusalem, until he was called with his friends in the HL department to send help to the besieged Gush Etzion. After an arduous journey on foot in the dead of night, when they were loaded with ammunition and medical aid, all thirty-five fell in a heroic battle, on the fifth day of Shvat, XNUMX, and Tobiah was among them.

In his estate, there remained a valuable herbage of the wild plants he had collected from all over the Land of Israel. Over the years it was found in the herbarium, the reserve at the Hebrew University, that half of the 300 species of plants considered rare were collected by Tovia. The 30 species of plants he discovered was a novelty to the knowledge of the flora of our country. Two who were new to science were even named in his memory and by his name: Satvanit Tovia, whom he discovered on Mount Herod (Herodion), and Iris Tovia, whom he discovered on Mount Negev.

He was interested in the mosses of the Land of Israel and collected them for years since his youth, planning to create knowledge about their systematics, ecology and physiology, which did not exist in Israel at the time. In the large collection he left behind, it was later found that Tovia collected half of the moss species of our country. In the Newmythian species, "Ephemerum Yossov", which he collected in 1943 in Pardes-Hana, a type with larger spores than those of the common type of the species was found, and he and the French moss researcher Bizot defined the type as a new species for science: Ephemerum sessile var. Kushniri.

The large collection of butterflies created by Tovia is mentioned in the introduction written by Prof. Aharon Sholov to the book "Butterflies of the Land of Israel" by Yitzchak Eisenstein as "the most complete collection of butterflies and flutterers" in the country. It was a collection that was a milestone in the study of the butterflies of the Land of Israel after the collection of butterflies and moths of Israel Aharoni, the first Hebrew zoologist and the first definer of the "Bnei Shemesh" Yom butterflies prepared by Aharon Katzir. One of the butterfly species that Tovia collected on Mount Hermon in 1947 has not been found in Hermon since then until today. In memory of Tovia, butterfly researcher Dobi Binyamini named this butterfly "Tovia nymph".

Tovia's research, tour diaries, travels and letters were collected in the book, "Nature Studies and Letters". From the book of his estate, it was revealed that despite being a naturalist, a man of the exact life sciences, Tovia was endowed with a sensitive soul, a thirst for beauty and a rare ability to express herself, in front of the beauty of nature she spoke and wrote poetry. If in front of a hidden beauty hidden in a greenish patch of rare moss, certainly in front of the majesty of blossoms in all their shades - in the irises of his hearts and orchids, and even in front of a biochemical scientific text as on breathing - seemingly dry - he knew how to admire and bring out from it the beauties of nature in its overall and complete picture.

As a result of reading his book, readers came for years both to our father's house and to his grave on Mount Herzl in Jerusalem, who expressed a vibration of admiration for his character who gave them inspiration and direction in life. Tovia's sense of disaster and loss and the records of his short life's achievements accompany his memory to this day. His teacher Prof. Elisheva Goldschmidt, the founder of the science of genetics in our country and winner of the Israel Prize in Natural Sciences, saw him as a genius. About him she wrote "What he could have done and accomplished at the height of his development for the advancement of science and the nation - cannot be assumed."

On the 60th anniversary of his fall, at the memorial day held at the Hebrew University on Mount Scopus, his childhood friend Prof. Yigal Ptolemy participated, who at the end of his speech said: "In the War of Liberation, 600 students from the Hebrew University on Mount Scopus fell. Many of them had talents, who could contribute so much to culture and science in our country. At the same time, there was not a single fall - like the fall of Tovia Kushnir - in the loss caused to the world of science."

And yet, his short and wonderful life of 24 years was a life of value, of meaning and meaning. A life for the knowledge of nature and the discovery of its north, for the exploration of the landscapes of his homeland in the animal and plant kingdom, as part of the revival of his people in the land of his ancestors, where he tragically-heroically met his death in the spring of his days.
last letter

XNUMX Tivat, XNUMX.
Ma'ale Ha'Hahime (there he was with the Palmach company from the Harel Brigade in training and securing the convoys on the way to Jerusalem - until they left for Gush Etzion)

Hello, dear father*,
This is the third day I have been outside of Jerusalem. Here between winter storms and stormy winds, calm even sunny days, spring-mountain days. And between the invaders of the forest and between the cliffs rise the daisies ["the maiden daisy" in the language of our day], these are the flowers of the radiance of the mountains. On the now bleaching slopes, the cypresses are laden with flowers, sedges and daffodils. A memory of days rises - and their memory is erased, when a silent sorrow flutters in the heart. Here, nature is like a day in its prime - and even man, and probably he is also a day in a day - he is also in his time - and the values ​​are identical.

It is so strange to imagine that somewhere the normal life still continues, and more plowing and sowing in the long run. It seems that only the earth has the power to wrap its workers in thick cables. It's strange now, very strange to think about studies and research, and the plans, there were so many plans! It's good that at least I finished and sent the research to Arzavim, the work must have already been published [published in the journal Nature in England, A.K.], and the copies of the article sent to me [The Days of Events and Train Robbery, A.K.] have already been burned in someone's fireplace The friends - and a perfume for him.

I have one now, and all those problems of chromosomes - and hybridization of plants and half-finished and quarter-finished works, after all, they are so far away... I have and occasionally have free hours for the whims of the spirits, so when I can't sit on the glowing carpets of grass, look at the "strange" peace of colorful flies, which suck flowers Bat Hachan - I open a wonderful book on biochemistry and read two or three pages. And the book is wonderful among the wonderful, a dynamic approach is taken to detail the processes of life, and you will be carried along with it at an appropriate pace and penetrate the wonders of the secret of life. Movement, sense and breath are suddenly seen in a general light that is in me, a vast creation, which came as the result of a long period, spanning all the millions of years of life's existence, of attempts and failures, attempts and achievements. Here evolution is revealed in all its glory, as it manifests itself in each of the life processes.

And more than I read, reading brings me to immerse myself in reflections, so that even in these days there are points, which give something of the joy of life. Although I know that the act I am doing today is the only one that can give a Jewish boy a trace of satisfaction, nevertheless the days remain gray, because I do not see myself - to use the language of S. Yizhar - a brave hero, even though I know that the actions I may perform tomorrow or the day after tomorrow will be described as very "intense". And peace to all the members of the house, from her best.

* Tovia's father was the pioneer and writer Shimon Kushnir (1895-1986)

* Source of the title of the article: Shaul Tschernihovsky: "Rai Adama"
for further reading

* Tovia Kushnir, Nature Studies and Letters, Am Oved Publishing House, XNUMX. Expanded and revised second edition edited by Micah Levana - a publishing house of the Ministry of Defense, XNUMX.

* Shimon Kushnir, The Irises Are Still Blooming, Em Oved Publishing House, XNUMX.

* Eliezer Shamali, "Tovia the Hunter of the Engagements", Children's Book Volume MA, 1971

* Ofer Cohen, "Tobiah Sethonit and other flowers", At-Mol Volume 1991, XNUMX XNUMX.

* Nurit Kirsh, "The beginnings of genetics at the Hebrew University, 1961-1935". From: The History of the Hebrew University in Jerusalem - Strengthening in the midst of a national struggle, (Editor Hagit Levsky), Magnes, Jerusalem, XNUMX.

* Nurit Kirsh, "Between paralysis and momentum of action: scientific activity during the war." From: Citizens at War - A Collection of Studies on Civil Society in the War of Independence (Editors Mordechai Bar-On and Meir Hezkan), Jerusalem, 2010.

MJD White (1954), Animal Cytology and Evolution (2nd ed.) Cambridge University Press. 454 p.

MJD White (1978), Modes of Speciation, San Francisco, Freeman, 455 p.

* Dr. Uri Kushnir is a researcher at the Plant Sciences Institute, Agricultural Research Administration - Volcanic Center.