140 



ARCHEGONIATES. 



the others lay in the cytoplasm of the receptive spot (Fig. 56, C). 

 (In this figure one of the spermatozoids was cut in sectioning, so that 

 only two separate pieces of it are shown, the other parts being in the 

 next section.) The nucleus was concave above, but the egg-cell had 

 not collapsed. It remained apparently turgid, having been only 

 slightly shrunken uniformly on all sides by the reagents. The mem- 

 brane of the egg seemed to be firm, but whether it was anything more 

 than a plasma membrane I was unable to determine. The prothal- 

 lium from which this preparation was made was killed in chrom-acetic 



E 



FIG. 56. Fusion of sperm and egg-nucleus. C, Onoclea 

 struthiopteris ; D and E, Onoclea sensibilis. 



C, vertical section of egg ; two spermatozoids have pene- 



trated egg, one of which is just entering egg-nucleus ; 

 the egg is globular, but its nucleus is concave above. 



D, vertical section of egg; outside spermatozoids arc 

 forced against venter wall by expanding egg ; sperm 

 nucleus within egg-nucleus has begun to reticulate ; 

 three hours. 



E, horizontal sectional section of an egg; fourteen hours. 



(D and E, after Shaw.) 



acid, and, although stained on the slide with Bismarck brown in addi- 

 tion to the Flemming triple stain, there was nothing to indicate with 

 any certainty a cellulose character of the membrane. Lying in the 

 cytoplasm near the nucleus of each spermatozoid was a delicate thread 

 which seemed to be the blepharoplast. The cytoplasmic reticulum 

 was somewhat shrunken from the membrane of the egg on one side. 

 In another preparation mentioned in a preceding paragraph the open- 

 ing of the neck of the archegonium was apparently closed by a plug of 

 spermatozoids after one had entered. This spermatozoid lay against 



