222 BYRNES. [Vol. XVI. 



but not until after the spindle has already formed. Hence, in 

 the formation of the second maturation spindle, only the mantle 

 fibers of the spindle could be formed from nuclear substance, as 

 Flemming and Reinke maintain. 



I am unable to determine the precise method by which the 

 chromatin is brought into the equator of the second polar 

 spindle. It seems, however, as if it must be effected by some 

 of the polar rays that come secondarily into contact with the 

 chromatin, and thus become transformed into mantle fibers. 



V. Structure of the Cytoplasm : Archoplasm. 



The very coarse cytoplasmic network that is often seen in 

 the Q.^% of Limax is probably not characteristic of the living 

 ^SS- -^ coarse reticulated appearance is nearly always found 

 in eggs that have been preserved in corrosive sublimate acetic 

 solution, and is in all probability due, in part, to precipitations 

 that are formed when the eggs are killed. This structure of 

 the cytoplasm occurs in eggs that are apparently perfectly 

 preserved and that show the finest details of structure in the 

 astrosphaeres (PI. XI, Figs. 2, 5, and 10). Probably a truer 

 representation of the structure of the cytoplasm is seen in those 

 eggs that were hardened in Flemming's solution after they 

 had been killed in corrosive sublimate acetic solution. These 

 eggs show no distinct reticular structure, but minute varicosi- 

 ties are distinguishable on threads of the utmost fineness. The 

 general appearance of such a preparation is granular rather 

 than reticular, although the filamentous nature of the cyto- 

 plasm in the preserved material is still faintly discernible. In 

 these eggs the astral rays are extremely delicate, and the details 

 of the centrosphere are clearly shown. 



The peculiar structure of the centrosphere, particularly at 

 the stage of the archiamphiaster, cannot be due to the method 

 of preservation of the eggs, for it is constantly present, no 

 matter with what reagent the eggs have been killed. Prepara- 

 tions have been made of eggs that were killed in Flemming's 

 solutions, in corrosive sublimate acetic (5 per cent), in chromic 

 acid (i per cent), and in Flemming's solution after corrosive 



