GYMNOSPERMS. l6l 



while the cilia motion continues probably some time longer, carrying the band 

 farther along and freeing the nucleus from any hindrance by it. The apex of 

 the spiral end of the spermatozoid invariably enters the egg-cell first, and in all 

 of the cases observed where the nucleus has just escaped from the spermatozoid 

 it has been found a short distance behind the spiral of the spermatozoid, as if 

 it had been forced out and left behind. The function of the cytoplasm of the 

 spermatozoid is still in considerable doubt, but that it fuses with the cytoplasm 

 of the egg-cell is certain. Shortly after the nucleus has broken out of the sper- 

 matozoid cell, the thin layer of dense cytoplasm which surrounded it can be 

 seen in a broken, fragmentary form, still somewhat connected with the spiral 

 band. The cytoplasm of the spermatozoid in this stage is very different from 

 that of the egg-cell, being more densely granular and staining more deeply, so 

 that it is easily distinguished. Later, only a coarse granular substance is found 

 inside the spiral coil of the ciliferous band, and it would seem that this is the 

 cytoplasmic matter from the spermatozoid which has mingled with that of the 

 egg-cell. It should be mentioned that the plasma membrane surrounding the 

 spermatozoid has entirely disappeared, no trace of it being visible. It would 

 seem to have fused with some substance of the egg-cell or to have been 

 absorbed in some way. 



The male nucleus, when it has escaped from the spermatozoid and is observed 

 lying in the cytoplasm at the apex of the egg-cell, is a loose, open structure, 

 seeming to have but little kinoplasmic and chromatin matter. The passage to 

 the nucleus is evidently a rapid one, as few stages have been found between 

 the above and the completion of fecundation. In some instances the path over 

 which the nucleus travelled in reaching the egg-nucleus is discernible by the 

 arrangement of the granules in the cytoplasm, showing the direction of the 

 passage. 



The egg-nucleus, previous to fecundation, is elliptical and is located slightly 

 below the center of the enormous egg-cell which is about 3 mm. long by 1.5 mm. 

 wide (Fig. 66, A, B). The egg-nucleus is of enormous size, comparatively, 

 being plainly visible to the unaided eye. It is composed of an open, coarse 

 reticulum. So far as the writer has observed there is no depression or " emp- 

 fangnisshohle " in the upper part of the nucleus where the sperm-nucleus enters, 

 as was found by Ikeno in Cycas. No special attention has been given to this 

 matter, however, and further observation may show it to be present. The male 

 nucleus in entering the egg-nucleus gradually pushes into it as observed by 

 Ikeno in Cycas, and finally becomes entirely surrounded by it. Meanwhile it 

 has changed its structure and become densely granular, differing markedly 

 from the egg-nucleus in this particular. . . . After fecundation is apparently 

 completed the male nucleus appears as a small, nearly round body in the upper 

 portion of the egg-nucleus into which it has penetrated (Fig. 66, B). 



Further changes in the sexual nuclei were not followed by Webber, 

 and it is not known whether a fusion nucleus is formed in Zamia as 

 described by Ikeno for Cycas. 



Since the publication of his paper on Cycas, Ikeno ('01) has observed 

 the formation of the ventral canal-cell, the process of fecundation and 



