290 N. M. Stevens. 



I had no difficulty in finding Elpatiewsky's 'besondere Korper' 

 in the free eggs of Sagitta elegans, provided that they had reached 

 the stage when the two pronuclei were in the center of the egg, as 

 in Fig. 24. Fig. 28 shows this body from the same egg as Fig. 

 24, and Fig. 29 a and h is another similar stage, while Figs. 30 and 31 

 are sections from 2-cell and 16-cell stages. It was also found in 

 all stages between those of Figs. 29 and 31, but when I cam.e to 

 look for it in earlier stages, of which I had an abundance, both 

 of Sagitta elegans and of Sagitta bipunctata, no connection be- 

 tween the 'besondere Korper' and the accessory fertilization cell 

 could be traced. Figs. 32 a and 6 show an egg in which the acces- 

 sory cell {a) is evidently degenerating, and the nucleus of the egg 

 is breaking down preparatory to the first maturation mitosis; 

 Figs. 33 a and h another egg, still attached, with the first matura- 

 tion spindle in prophase. In the latter case the nucleus of the 

 accessory cell looked quite normal, while in the former the whole 

 cell stained dark and a somewhat lighter portion in the center of 

 the cell was the only indication of the disappearing nucleus. In 

 general it may be said that at this stage the accessory cell looks 

 shrunken and dark, and the nucleus has either degenerated or is 

 on the point of doing so. Fig. 34 shows an egg in which the two 

 accessory cells were both much shrunken when the first maturation 

 spindle was in metaphase. In such a stage as Fig. 32 a the acces- 

 sory cell is about the same size as the ' besondere Korper' (Fig. 29) 

 , and both stain deeply. The accessory cell, however, has a dis- 

 / tinct cell boundary and the 'besondere Korper' quite a different 

 structure, being composed of a non-staining homogeneous matrix 

 filled with deeply staining granules. Fig. 35 shows one case 

 where this body was not spherical but irregular in outline, con- 

 sisting of somewhat scattered masses, at a stage when the first 

 segmentation spindle was in metaphase. 



In maturation stages between Figs. 32, 33, 34, and Fig. 29, I find 

 absolutely no trace of either accessory fertilization cell or 'beson- 

 dere Korper.' This is in entire argeement with the conclusion of 

 Elpatiewsky, and is based on examination of many preparations 

 of Sagitta elegans (1904 material) in which eggs containing the 

 first maturation spindle in metaphase were passing down the ovi- 



