Graduate Studies at Columbia University

Sutton's move to New York to work on a doctorate in Zoology occurred through the encouragement and help of McClung and Dr. Samuel W. Williston. They both knew Edmund B. Wilson and believed Sutton was ideally suited to study with this well-known cytologist. McClung knew Wilson having spent a semester in graduate studies with him before receiving his MA in 1898 from Kansas. And Williston, a physician, chairman of anatomy and Dean of the two-year medical school that was formed in 1899 at the University of Kansas, knew Wilson from student days at Yale where Williston obtained his MD in 1880. As Williston later recalled Sutton, "His zeal, intelligence and interest from the beginning made him a marked member of my classes." When Williston found that Sutton was deeply interested in the study of the cell and wanted to continue cellular investigation, he later stated, "there was but one place for him to go, Columbia University, New York, with Professor Wilson." Williston recalled, "I knew not only his great and just fame as a scientific man, but I knew him also as a friend, and felt free to write him in Walter's behalf... I told him that, of all the students I ever had in my classes, there was none who, intellectually and personally, reminded me so forcibly of an old friend of mine, whose name was E. B. Wilson," (Williston, Family memorial).

Samuel B. Williston, Sutton's instructor in human anatomy, was largely responsible for Sutton's acceptance to Columbia University by way of a recommendation to his friend E. B. Wilson. (Courtesy of the University Archives, Univ. of Kansas Libraries.)

Sutton received a graduate fellowship in Zoology at Columbia University in the fall of 1901, the first student West of Mississippi to receive this recognition. He brought his cytological preparations and recorded observations into Wilson's laboratory. Wilson wrote: "His work in my laboratory was largely devoted to extending those observations. They led him, step by step, to a discovery of the first rank, namely, the identification of the cytological mechanism of Mendel's law of heredity." (Wilson, Family memorial). This discovery was revealed in two papers in the Biological Bulletin, one in December of 1902, "On the Morphology of the Chromosome Group in Brachystola Magna," (Sutton, 1902) the other in April, 1903, "The Chromosomes in Heredity" (Sutton, 1903). In the first of these two papers, Sutton methodically carries the reader through the crucial theme that chromosomes retained individuality throughout the life of the organism. He does this by following the size relationships of eleven chromosomes through consecutive cell generations during spermatogenesis where a subgroup of three small chromosomes is consistently separated from eight large chromosomes. Since fertilization unites homologous chromosomes, he anticipates that the same chromosomal size relationship is persistent in oogenesis. He then reports his observations that the graded sizes of chromosomes in oogonia and in follicle cells correspond perfectly with that of spermatogonia. The accessory chromosome was identifiable in half the spermatozoa, providing additional evidence for the individuality of the chromosomes. Since McClung showed that the accessory chromosome in some way confers sexual identity to the offspring (McClung, 1899) (McClung, 1902), Sutton made a more generalized suggestion that not only is each chromosome consistently distinct by virtue of size but that it may be physiologically unique as well. This was summarized by Sutton in the following way: "We have already reviewed the reasons for believing the accessory chromosome in the cells of Brachyostola to be the possessor of specific functions and it only remains again to call attention to the likelihood that the constant morphological differences between the ordinary chromosomes are the visible expression of physiological or qualitative differences" (Sutton, 1902). At the end of this paper, Sutton presents his hypothesis. "I may finally call attention to the probability that the association of paternal and maternal chromosomes in pairs and their subsequent separation during the reducing division as indicated above may constitute the physical basis of the Mendelian law of heredity" (Sutton, 1902). The writing of this paper coincides with a visit to New York by the leading figure of the day in heredity research, William Bateson, who that year published a translation of Mendel's Principles of Heredity (Bateson, 1902). Bateson was spreading the word on the rediscovery of Mendel's principles and Sutton may have seen for the first time how these principles related to his work. McClung and Sutton corresponded during this period and McClung writes that Bateson's presentations on Mendel had a striking impact on Sutton. "This was all that was needed to fix in his mind the relation between the mechanism of the germ cell and the exhibition of body characters, and led him almost at once to the conception of the theory which appears in his paper "'The chromosomes in heredity'" 1903, the basis for which was laid in his earlier paper, "'On the morphology of the chromosome group on Brachystola magna,'" 1902." Based on a letter from Sutton, McClung stated that ... "the germ of the conception was in his mind fully a year before it was hastened to development by the recital of Mendel's results." (McClung, Family publication). The originality of Sutton's thinking at this time is all the more impressive when we read Wilson's recollections of this period. "I well remember when, in the early spring of 1902, Sutton first brought his main conclusions to my attention, saying that he believed he had really discovered "'why the yellow dog is yellow.'" I also clearly recall that at that time I did not at once fully comprehend his conception or realize its entire weight." In the summer of 1902, Wilson and Sutton collected and studied marine specimens at Beaufort, N.C. and later at Casco Bay, ME. Wilson states "....(it was) in the course of our many discussions, that I first saw the full sweep and the fundamental significance of his discovery." (Wilson, Family memorial).

>Edmund B. Wilson, 1856-1939. Sutton's mentor at Columbia University and leading cytologist of the period. He named Sutton's conclusions, that chromosomes are the physical basis of inheritance, the "Sutton-Boveri hypothesis". (Courtesy of the Columbia University Archives).

The experiments of Wilson's graduate students, Sutton and W. A. Cannon (Cannon, 1902), both pointed to the relationship between chromosome behavior and heredity and he wrote a short paper on their findings (Wilson 1902). During that summer, Sutton fully worked out his theory of chromosomes in relation to Mendel's laws and on returning to New York he prepared the more inclusive paper, "The Chromosomes in Heredity" (Sutton 1903). This paper is remarkable in the manner in which Sutton builds his arguments and for his insight into the consequences of chromosomes behavior during meiosis. He provides a table of the possible number of chromosome combinations for different chromosome numbers based on the random selection of a male or female chromosome in the reducing division of meiosis. The concept of a mixture of parental and maternal chromosomes in the gametes was not in the 1902 paper and was probably based more on the realization of how it explained Mendelism than what he saw under the microscope (Martins, 1999). Also, he favored the presence of multiple hereditary characters on one chromosome in explaining the coupling of characters reported by Bateson and Saunders (1902). He states, "Such results may be due to the association in the same chromosomes of the physical bases of the two characters" (Sutton, 1903). However, he did not anticipate cross-over, the exchange of parts of maternal and paternal chromosomes, because he believed this would result in infertility. The chromosomal theory of inheritance is known as the Sutton-Boveri theory. Wilson had close ties with Boveri that probably accounted for Wilson's adding Boveri's name when he named the hypothesis. Wilson related that, "Subsequent to the appearance of Sutton's papers, Boveri stated, 1904, that at the time they were published he had himself already reached the same general result." (Wilson, Family memorial). He was a close friend of Boveri, spent time in his laboratory and dedicated his book, "Cell in Development and Inheritance" (Wilson, 1900), to him. In 1897, Miss O'Grady, a student of Wilson's at Columbia University, came to Wurzburg to work with Boveri. In 1898 they were married, and as a zoologist, she was an important collaborator. It seems Wilson wanted to give lasting credit to Boveri for his years devoted to the study of chromosomes in development, including his demonstrations of the individuality of chromosomes (Baltzer, 1964) but recognize Sutton for presenting the first physical (chromosomal) explanation of Mendel's laws. "Sutton, however, was the first clearly to perceive and make it known; and I desire here to bear witness to the fact, after having followed every step of this work on the subject, that the conception was his own, wholly uninfluenced by the work or the ideas of others excepting insofar as every important discovery has been built upon a foundation laid by earlier investigators;....."(Wilson, Family memorial). Most scientists in the field, particularly cytologists, readily accepted Sutton's hypothesis. Noteworthy was the lack of initial acceptance by two leaders in the field, Bateson and Thomas Hunt Morgan. This is understandable in that the individuality of chromosomes and the manner of chromosome separation during meiosis described by Sutton only provided a working mechanism for Mendel's laws. Other than the sex determinant of the accessory chromosome, proof of characteristics on chromosomes was slow in coming. Seven years later Morgan accepted the hypothesis when he found that the unusual occurrence of a white-eyed fruit fly was due to a mutation on a sex chromosome (X-chromosome) (Morgan 1910). Bateson's non-acceptance of the chromosome hypothesis of heredity was longer (19 years) but he could not refute Morgan's accumulating evidence and in an address to the AAAS, December 28, 1921 he stated, "The transferable characters borne by the gametes have been successfully referred to the visible details of nuclear configuration." (Bateson, 1922). The Sutton papers of 1902 and 1903, referred to above, were planned as preliminary presentations with more fully developed conclusions and finished drawings reserved for his Ph.D. thesis. However, Sutton, now 26, left Columbia University to the regret of Wilson and others. The reasons for his leaving are not clear, although Wilson believed if he would have been assured a reasonable living from a life of research he would have stayed (Wilson, Family memorial). It is as likely that he saw oil exploration as a new arena to apply his creativity, a side-trip before returning to medicine.