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SCIENCE 



[N. S. Vol. XLIII. No. 1104 



an investigator soon attracted scores of stu- 

 dents to the quiet laboratory in Wuerzburg, 

 many of them coming from this country. One 

 of the first, Miss O'Grady, of Vassar College, 

 became his faithful wife, the mother of his 

 daughter and an efficient assistant in all his 

 later scientific work. 



It is hardly necessary to add that with his 

 growing fame came numerous honors con- 

 ferred on him by his university, where he 

 held the highest office as rector magnificus in 

 1909, by his government and by learned soci- 

 eties. Among the learned societies which con- 

 ferred on him their membership is the Amer- 

 ican National Academy of Sciences. 



When Weismann resigned his professor- 

 ship in Freiburg Boveri was called to succeed 

 him, but declined. Later the directorship of 

 the new research laboratory of the Kaiser- 

 Wilhelm-Gesellschaft in Berlin was offered to 

 him. He first accepted, worked out the whole 

 organization and brought together the staff; 

 but suddenly he declined again. Possibly he 

 already felt that his health was no longer 

 vigorous enough for such a change. When 

 I saw him for the last time, two years ago, in 

 Naples, he gave me the impression of a 

 strong and healthy man, but within a short 

 time a disease of the gall-bladder forced him 

 to interrupt his teaching for a year. An op- 

 eration performed in the first days of October 

 could not save his life. 



When Boveri entered the field of biological 

 research in the middle of the eighties the sci- 

 ence of cytology was just outgrowing its child- 

 hood. Only ten years previously the funda- 

 ments had been laid. After certain incidental 

 observations, especially by A. Schneider and 

 Auerbach, Otto Buetschli collected his re- 

 sults on the division of the cell, the matura- 

 tion and fertilization of the egg and the 

 conjugation of Infusoria in his classic work 

 of 1876. From that time dates the knowl- 

 edge of the karyokinetic division of the 

 cell with all its consequences. At about the 

 same time appeared O. Hertwig's classic work 

 on the fertilization of the sea-urchin egg, ma- 

 king it clear for the first time that fertiliza- 

 tion is the union of egg- and sperm-nucleus. 



Then followed one fundamental discovery 

 after another. Strasburger soon applied the 

 new facts to the cells of plants. Flemming 

 (1882) worked out the details of the mitotic 

 figure, introduced the term " chromatin " and 

 discovered the longitudinal splitting of the 

 chromosomes. Eoux (1883) realized the theo- 

 retical importance of the new discoveries and 

 pointed out the meaning of the mitotic divi- 

 sion of the cell, anticipating practically all of 

 the views of to-day. In 1884 Heuser for plants 

 and Van Beneden for animals were able to 

 prove that the separated halves of the chromo- 

 somes are distributed to the daughter cells. 

 (The word chromosome was first introduced 

 in 1888 by Waldeyer.) At the same time 

 Naegeli (1884) developed his ingenious theory 

 of the idioplasm, and soon Strasburger, Koel- 

 liker, O. Hertwig, Weismann pointed to the 

 chromosomes as the seat of the material basis 

 of heredity. Only one important step was 

 still lacking, the full understanding of 

 the process of fertilization. Mark (1881) 

 came very near to making this discovery, but it 

 was Van Beneden (1884) who proved that in 

 fertilization the same number of paternal and 

 maternal chromosomes are handed over to the 

 cleavage cells. These discoveries were made 

 on the eggs of Ascaris, studied previously by 

 A. Schneider and Nusbaum, and which have 

 since become one of the classic objects of 

 cytology. One after the other followed in 

 those days the discoveries, which elucidated 

 the whole process; the meaning of the polar 

 bodies (Buetschli, 0. Hertwig, Giard, Mark) ; 

 the parallelism between ovogenesis and sperma- 

 togenesis (Van Beneden et Julin) ; the theory 

 of the reduction division (Weismann) ; the 

 behavior of the polar bodies in parthenogenesis 

 (Blochmann, Weismann and Tshikawa) ; the 

 continuity of the germ-plasm (Nusbaum, 

 Weismann) ; the individuality of the chromo- 

 somes (Eabl) ; and finally, in 1887, the founda- 

 tion of experimental cytology by 0. and E. 

 Hertwig. This was the year when Boveri's 

 first " Zellstudien " appeared. 



Under the influence of Van Beneden's classic 

 book, Boveri began by studying the sex cells 

 of Ascaris. In his Zellstudien, I., 1887, he 



