32 Society for Experimental Biology and Medicine. 



6. The most general modification of the mitotic figure is the 

 production of polyasters, multipolar spindles, and as a consequence, 

 multiple nuclei. In many cases the cells are filled with asters and 

 irregular mitotic figures, during division, while in the resting stage 

 they are filled with equally numerous resting centrosomes and 

 nuclei. 



7. The movements of the chromosomes are in many cases inter- 

 rupted, so that they remain scattered along the spindle, while the 

 cytoplasmic movements are frequently stopped or altered. 



8. In some cases the achromatic portion of the nucleus is 

 separated from the chromatic part, and the two may persist side 

 by side during the resting stage of the cell ; in the division stages 

 the achromatic nuclei give rise to asters, the chromatic to chromo- 

 somes and both may divide indefinitely, giving rise to large num- 

 bers of chromatic and achromatic nuclei. 



9. The most general modification of the division of the cell- 

 body is the suppression of the cleavage of the yolk ; this occurs 

 in practically all the experiments ; at the same time the cleavage 

 may proceed more or less regularly in the protoplasmic portion 

 of the egg. In normal eggs the first and second cleavages divide 

 the yolk into four equal cells (the macromeres) and, from each of 

 these, three small cells (the micromeres) are budded off. 



10. If the yolk remains undivided it gives rise in certain cases 

 to three micromeres, which have the characteristics of those formed 

 from each of the four macromeres of the normal egg. If the yolk 

 has divided once so as to form two macromeres, each of these may 

 give rise to three micromeres, having the characteristics of the 

 three quartet cells of the normal egg. In short, the number of 

 micromeres depends upon the number of macromeres. When there 

 are four of these as in normal eggs, the micromeres are formed in 

 three quartets ; when there are two, they are formed in three pairs ; 

 when there is but one macromere, i. e. t when the yolk remains 

 undivided, the micromeres are formed singly. 



11. When eggs are subjected to pressure the third cleavage 

 which normally gives rise to the first group of micromeres, may 

 divide one or more of the macromeres equally, thus giving rise to 

 five, six, seven or eight macromeres. If the pressure is removed 

 from such eggs each macromere gives rise to three micromeres in 



