204 BYRNES. [Vol. XVI. 



clear zone of the centrosphere, with its central granule or 

 granules, corresponds to the centrosome of Boveri (PI. XI, 

 Figs. 2, 3, and 6). 



2. Ovarian Eggs. 



I have not attempted the study of the ovogenesis of Limax, 

 My attention was directed to the ovarian eggs in the hope of 

 finding in them the origin of the granular centrosomes of the 

 archiamphiaster ; for it was evident that the centrosomes ap- 

 peared before the eggs were laid. I dissected a number of 

 individuals and found several of them with eggs arranged in a 

 row along the oviduct. The capsules had already been secreted 

 about these eggs, which contained a well-formed amphiaster. 

 Other individuals were dissected and were found to contain 

 eggs in the lower part of the duct of the albuminous gland ; 

 these eggs had no capsules, but each egg contained an amphi- 

 aster. It was evident then that the origin of the centrosome 

 must be looked for at a still earlier period. 



I then sectioned the ovo-testis of Limax and found several 

 eggs in the archiamphiaster stage. These eggs were in the 

 lumen of a follicle that was filled with spermatozoa. They 

 showed nothing of the origin of the centrosome, however, for 

 the spindle was already fully formed (PI. XI, Fig. 2). In Fig. 2 

 no trace of the germinal vesicle remains, the chromatin being 

 already in the equatorial plate stage. Even at this early period 

 the centrospheres are precisely like those of the newly laid 

 ova; they have a clear central ("medullary") zone, in which 

 two oblong deeply staining centrosomes are distinctly shown, 

 and a periph( ral (" cortical ") zone which stains almost black 

 with iron-haematoxylin. 



The peripheral zone ("archoplasm " of Boveri) shows a very 

 strong affinity for Lyons blue when stained with this dye and 

 borax-carmine. PL XI, Fig. i, shows a section of an ovarian 

 Qgg in which the center of the aster is still undifferentiated. 

 There is no distinct centrosphere or centrosome present, and 

 the rays are short and relatively few in number. Unfortu- 

 nately the series of sections through this egg is incomplete, so 

 that I cannot make any statement in regard to the condition 



