530 MONTGOMERY. [Vol. XV. 



Wager ('93, Agarictis) describes the nucleoli as becoming 

 dissolved in the caryolymph, and then, this dissolved substance 

 penetrating the chromatin elements, the latter serve to carry 

 it over into the daughter-nuclei. Went ('s?, plant cells) holds 

 " dass in vielen Fallen wenigstens der Nucleolus beim Anfang 

 der Kerntheilung im Kernfaden aufgenommen wird," and that 

 " er sich nach der Theilung auch wieder daraus bildet." 

 Riickert ('94, egg of Cyclops) finds that the nucleoli gradually 

 break into fragments and the latter disappear. But there is 

 not space here to mention all the views of students of mitosis. 



There are only a few observations which would show that in 

 mitosis the chromosomes are derived from the nucleoli (David- 

 off, Vejdovsky, Blochmann, Marshall, Sobotta, '95, Macallum, 

 '95, Carnoy, '97a, R. Hertwig, '96, not corroborated by Brauer, 

 '94), and these cases stand in such marked contradiction to the 

 observations of other morphologists that a reinvestigation of 

 them is very necessary. ^ Then we have the observations of 

 Carnoy, Meunier, and Moll, which would show that the chro- 

 mosomes are derived from a part of the nucleolus ; but the 

 existence of a " nucl^ole-noyau," i.e., of a nucleus within a 

 nucleus, as assumed by Carnoy and his followers, in any meta- 

 zoan cell, seems to be very problematical. On the other hand, 

 most observers agree that the nucleoli disappear more or less 

 gradually during mitosis, and that the chromosomes are not 

 derived from them. Now we have reached the crucial ques- 

 tion : What is the mode of transference of the nucleolar 

 substance to the daughter-nuclei } In answer to this, some 

 observers hold that this substance may be distributed in the 

 cytoplasm and taken up therefrom into the daughter-nuclei; 

 others, that it combines with the chromatin elements and is 

 transferred with these; still others maintain a position inter- 

 mediate between these two.^ But when we find so much vari- 

 ance in the conclusions of competent investigators only one 

 deduction is allowable, namely, that the mode of transportation 



1 On the relation of nucleoli to chromosomes, c/. also Cunningham ('97), 

 Sobotta ('95), Macallum ('95), Plainer ('89c), Carnoy ('97a), R. Hertwig ('96), 

 Van Beneden ('83), Zimmermann ('96), Lauterborn ('96), Boveri ('88), Wheeler 

 (■97). 



2 C/. also Belajeff ('94), Mottier ('97), and Rosen ('95). 



