MOSSES AND LIVERWORTS 



103 



among the algse is found in the stoneworts (Characese), 



but the differences in the vegetative parts between these 



and the Hepaticse are too great to admit of the idea of 



any but the remotest 



relationship existing 



between the two, and 



at present it must be 



admitted that the 



gulf between Algse 



and Archegoniates is 



a very deep one. 



The antheridium is 

 not so different from 

 that of some algae, but 

 is much more com- 

 plicated than in any 

 but the Characese. In 

 the Archegoniates it 

 has the form of a 

 capsule (Fig. 26, C), 

 which in the lower 



forms is usually stalked. The central part is divided 

 into many small cells, in each of which is developed 

 a spermatozoid. The latter is very much like those of 

 most algse, and like them is provided with cilia (Fig. 

 26, D). 



Throughout the whole group of the Archegoniates 

 water is necessary for the opening of both archegonium 

 and antheridium, the water swelling up the mucilagi- 

 nous cell-walls of the interior of the organs, thus forcing 

 them open. The liberated spermatozoids then swim to 

 the open archegonium, which in the mean time has dis- 



3C. 



Fig. 26. — A, longitudinal section of the 

 archegonium of a liyerwort (Targionia), 

 showing the central row of cells ; B, a 

 similar section of the ripe archegonium 

 of Riccia ; the cells of the axial row are 

 disorganized and the egg, o, lies free in 

 the enlarged venter of the archegonium ; 

 C, longitudinal section of the antherid- 

 ium of Riccia, showing the mass of sperm- 

 cells surrounded hy a single layer of 

 peripheral cells ; D, a free spermatozoid 

 of Fimbriaria Californica. 



