CHAPTER VI. ARCHEGONIATES. 



The preceding chapters have been devoted to the process of fecun- 

 dation in various typical and well known Thallophyta, with the 

 exception of the Characece, if we may speak of this group as belonging 

 properly to the Thallophyta. Owing to the closer resemblance of 

 both sexual organs and gametes to those of certain Archegoniates, it 

 has been deemed best to refer to the Characece in connection with 

 those plants. 



Because of our meager knowledge of the development of the sperma- 

 tozoids, and the union of the sexual nuclei in liverworts and mosses, I 

 have omitted a discussion of the process in these groups and have dealt 

 more fully with sexual reproduction in certain Pteridophyta and 

 gymnosperms. 



The discovery of spermatozoids in Cycas by Ikeno and Hirase, and 

 in Zamia by Webber, and a more accurate knowledge of the develop- 

 ment of these structures in the Pteridophyta have aroused an unusually 

 keen interest in the study of the sexual cells and the phenomena 

 accompanying their union both in these and in the higher plants. In 

 presenting the phenomena relating to the sexual process in the Arche- 

 goniates, we shall confine ourselves largely to Onoclea and Gymno- 

 gramme among the Pteridophytes and to Cycas, Zamia, Ginkgo, 

 and Pinus of the gymnosperms ; for it is in certain species of these 

 genera that the process, in so far as it has been followed with the use 

 of later methods of research, is best known. 



PTERIDOPHYTA. 



Until recently the spermatozoid of the Pteridophyta was generally 

 conceded by many of the most competent investigators to consist 

 merely of a transformed nucleus with cilia of an obscure cytoplasmic 

 origin. This view was due very largely to the methods of fixing and 

 staining used, which, as we now know, were inadequate to bring out 

 with definite clearness the more delicate cytoplasmic structures of the 

 cell. 



In recent years Belajeff, Shaw, and others have applied improved 

 cytological methods to the study of the development of the sperma- 

 tozoid in Gymnngramme, Onoclea, Marsilia and Equisetum. In 

 certain species of these genera, they have found that the mature 

 spermatozoid consists of a nucleus and a delicate band or wing of 



