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SCIENCE 



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



not the hereditary qualities are transmitted in 

 the nucleus. He therefore fertilized enu- 

 cleated egg-fragments of 8 phcer echinus with 

 the sperm of Echinus and raised the resulting 

 larvae to the pluteus stage. He believed he 

 was able to prove that these larvae exhibited 

 only paternal characters. It is well known 

 that the validity of this conclusion was at- 

 tacked by Morgan and by Seeliger. It was 

 not until 1896 that Boveri published, in Boux's 

 Archiv, the full account of this work and 

 answered the objections of his critics. To-day 

 we know from the work of many observers that 

 the question is not a simple one. But in this 

 paper we find incidentally another discovery, 

 taken up by Boveri much later; namely, the 

 dependence of the size of the larval nuclei 

 upon the number of their chromosomes. 



It is well known that during this first decade 

 of Boveri's work our science was revolution- 

 ized. In the years 1884r-88, Wilhelm Eous 

 had laid the foundations of the science of Ent- 

 wieklungsmechanik and the brothers Hertwig 

 had started their experimental work in cytol- 

 ogy and hybridization. Soon Driesch (1891) 

 imbued the new science with his philosophical 

 spirit, while J. Loeb (1891) attacked similar 

 problems from a physiological point of view. 

 Soon Morgan, Wilson and Herbst joined these 

 pioneers and this line of work henceforth made 

 itself felt also in all of Boveri's. 



After some smaller papers, dealing with ex- 

 periments relating to the theory of mitosis, he 

 published in 1899 a full account of the facts 

 relating to the diminution of the chromo- 

 somes, long since discovered by him.^ To 

 make all the facts clear he had to give a full 

 account of the cell-lineage of this worm, a 

 line of work of the greatest importance since 

 the discoveries of Wilson and Conklin in the 

 early nineties (although the foundations of 

 this line of work date back to the investiga- 

 tions of Eabl, Van Beneden and Whitman, as 

 is well known). The facts were in harmony 

 with the results of Zur Strassen, which* had in 

 the meanwhile been published. 



2 ' ' Die Entwicklung von Ascaris megalocepTwla 

 mit besonderer Buecksieht auf die Kemverhaelt- 

 nisse," Festschr. f. C. von KupfEer, 1899. 



The year 1900 brought the fourth part of the 

 Zellstudien, vsdth the subtitle " Ueber die 

 Natur der Centrosomen." The thirteen years 

 which had passed since the publication of the 

 first fascicle had seen an immense accumula- 

 tion of morphological and physiological facts 

 regarding the various parts of the cell, espe- 

 cially the chromosomes and the centrosomes. 

 The importance of these latter for the mechan- 

 ism of cell-division was already recognized by 

 Buetschli as early as 1876, in spite of the fact 

 that he did not realize them as distinct bodies, 

 riemming made this discovery, the significance 

 of which was realized, however, only when 

 Van Beneden and Boveri had discovered the 

 life cycle of these bodies and recognized them 

 as permanent organs of the cell, and after 

 Boveri had pointed to their important bearing 

 on the theory of fertilization. Since that time 

 a vast accumulation of knowledge concerning 

 the centrosomes had been acquired through the 

 work of Brauer, Coe, Griffin, Haecker, Heiden- 

 hain, Kostanecky, Lillie, MacFarland, Mead, 

 Meves, Van der Stricht, Vejdovsky, Wilson and 

 others. Boveri now deals with all the ques- 

 tions which had been raised, adding a series 

 of new facts about the life cycle of the centro- 

 somes in different objects. He discusses the 

 question of the nuclear origin of the centro- 

 some in the male sex cells of Ascaris, dis- 

 covered by Brauer and confirmed by Boveri's 

 pupil ITuerst. Then came the question of the 

 persistency of the centrosome in non-dividing 

 cells according to Heidenhain, and the centro- 

 some theory of the basal bodies of ciliary cells 

 as developed by Henneguy and Lenhossek. 

 Great importance was attributed to the ques- 

 tion regarding the phylogeny of the centro- 

 somes, discussed at this time in connection 

 with the discoveries in Protozoa by Buetschli, 

 E. Hertwig, Blochmann, Schaudinn and 

 Calkins. Fiu-ther he deals with the role of 

 the centrosome in the mechanism of cell-divi- 

 sion, which had been discussed broadly from a 

 physical standpoint during these years by 

 Buetschli, Heidenhain, Eabl, Ziegler and 

 Ehumbler, and defends his old earlier view- 

 point. Then he refuses Fischer's destructive 

 criticism of the methods of microscopical re- 



