202 BYRNES. [Vol. XVI. 



epoch-making classic on tiie maturation and fertilization of the 

 &g^ of Limax campestris. The studies of Warneck on the liv- 

 ing eggs of Limax agrestis, and of Mark on Limax campestris, 

 leave little to be added to the descriptions that have already 

 been given of the phenomena exhibited by the living eggs dur- 

 ing the early stages of development. When, however, the 

 eggs are preserved and sectioned, and then stained in haema- 

 toxylin after iron-alum, they show details of structure that 

 cannot be seen either in the living ^^g or in preserved eggs 

 studied in optical sections. 



It will be convenient in describing the maturation stages to 

 distinguish between the aster as a whole and the center of the 

 aster, which undergoes a series of changes that are apparently 

 independent of modifications of the astral rays. I shall, there- 

 fore, follow the terminology that Wilson has adopted in his 

 studies on the sea-urchin's ^g%, and use the term " astro- 

 sphaere " to designate the astral rays as well as the center 

 of the aster. For the center of the aster alone I shall reserve 

 the term " centrosphere." This terminology is employed only 

 for convenience in description, and has no significance based on 

 the recognition of a fundamental distinction between the two 

 parts of the astrosphaere. 



L Maturation of the Egg. 



I. TJie Archiamphiaster. 



The youngest eggs of Limax campestris that Mark studied 

 were those that had just been deposited. In these eggs a large 

 amphiaster, the " archiamphiaster " of Whitman and of Mark, 

 occupied the center of the egg. The eggs of Limax agrestis 

 agree very closely with those of Limax campestris in forming 

 the archiamphiaster before the eggs are laid. Sections of eggs 

 that have just been laid show that in the archiamphiaster stage 

 the centers of the asters no longer appear structureless, as in the 

 living egg, but are composed of distinct concentric rings or 

 zones, which react toward haematoxylin and other staining 

 reagents very differently from the rest of the cell. During 



