474 



WILSON. 



EXPLANATIONS OF PHOTOTYPES 1-4. 



Phototype i. The egg a few seconds after entrance of the spermatozoon, 

 showing the egg-nucleus above, the dark lance-shaped sperm-nucleus just inside 

 the lower periphery. A single sperm-nucleus lies outside at the upper right-hand 

 side. The entrance-cone lies at one side, and does not appear (cf. Text-fig. I, 

 A, p. 447). 



Phototype 2. The germ-nuclei approaching (about 5 minutes). Sperm- 

 nucleus rotated about 90°, with small sperm-aster lying at its base (Text-fig. I, C, 

 p. 447, is drawn from this specimen). 



Phototype 3. The germ-nuclei immediately before union (7 minutes), show- 

 ing growth of the aster. The branching of the astral rays and their microsomal 

 structure is shown at several points. Both the nuclei are slightly out of focus, 

 the object being to show especially the rays (cf. Text-fig. II, p. 449). 



Phototype 4. Soon after conjugation of the nuclei (10 minutes). From a 

 specimen double-stained with hasmatoxylin and acid fuchsin, which obscures the 

 rays, but shows clearly the central mass of the aster extending like a cap upon 

 one side of the egg-nucleus preparatory to its division. The sperm-nucleus appears 

 as a black body above the irregular egg-nucleus (cf. Text-fig. Ill, p. 450). 



