No. 2.] OOKINESIS. 229 



The whole series of movements and form-changes, progres- 

 sive and regressive, through which the nucleus passes in the 

 process of division, together with all the kinetic changes dis- 

 played in the germinal vesicle and pronuclei, are karyokinetic 

 phenomena. 



The phenomena which may be regarded as ookinetic, or 

 cytokinetic, display themselves in the vitelline protoplasm and 

 in the cytoplasm of cells in general. TJiey are diversiform in 

 the extreme, rarely presenting regular form-series, arid thus stand 

 in marked contrast with nuclear metamorphoses, which every- 

 where, both in plant and aiiimal cells, exhibit a most remarkable 

 tmiformity. This irregularity makes it quite impossible, in the 

 present state of our knowledge, to formulate, or express in 

 general terms, the phenomena embraced under this head. 



I. Movements of the Germinal Vesicle and 

 Pronuclei. 



The unique character of many of these cytokinetic displays 

 appears to me incompatible with the idea that they are the 

 direct effect of nuclear influence. Any changes in the proto- 

 plasm, induced and sustained at the expense of changes taking 

 place in the nucleus, should be as regular and uniform as the 

 karyokinetic processes themselves. On any hypothesis that 

 refuses to admit that the cytoplasm is endowed with subtle 

 powers of its own, and capable of automatic as well as respon- 

 sive action, how can we account for the characteristic difference 

 between telolecithal and centrolecithal eggs? By what power 

 are the passive yolk-elements restrained from taking the position 

 which they would assume under the influence of gravitation 

 alone ? What force drives the germinal vesicle from the centre 



regards the nucleus as a seat of energy, •which displays itself in phenomena of 

 mo tic 71. 



Mitosis is at best only a synecdochial expression, in which a part is put for the 

 whole. Allowing that the form-changes of the chromatic loops can be thus charac- 

 terized, it is evident that the movements of the achromatic elements are entirely 

 ignored. But, even in this limited sense, the word is not free from objection. Flem- 

 ming defines it as "thread-metamorphoses;" but Carnoy (^La Cellule, III., p. 319) 

 points out that, etymologically interpreted, it signifies " reduction to thread." 

 Now, it is during kinesis, or mitosis, as Carnoy justly remarks, that the chromatin of 

 the nucleus loses its thread-like form, breaking up into loops or rods, and resuming 

 its filoid aspect only after the division is completed. 



