THE VASCULAR CRYPTOGAMS 



67 



ever, are soon dissolved, and now the spermatozoids are 

 able to escape, and begin their active career. Each 

 spermatozoid drags with it, 

 attached to the hinder end, a 

 bladder - like sac, which is 

 derived from the inner part 

 of the protoplasm of the mother- 

 cell (see Figs. 33 and 34). The 

 locomotion is very active ; the 

 little spermatozoids go wrig- 

 gling through the water in all 

 directions, always keeping their 

 thin ciliated ends foremost; 

 they revolve on their axes, 

 and advance at the same time, 

 not in straight lines, but in 

 varying curved paths. Some- 

 times the little bladders are 

 left behind, sometimes they 

 hang on all the time, until 

 an archegonium is reached. 

 Before describing the ultimate fate of the spermatozoids, 

 we must now turn our attention to the archegonia. 



2. The Archegonia 



As we have already mentioned, the archegonia do 

 not arise so indiscriminately on different parts of the 

 prothallus as the antheridia do, but are limited to the 

 sides of the thickened cushion. An archegonium, like 

 an antheridium, arises from a single cell, which at first 

 projects only slightly above the level of the neighbouring 

 tissue. It divides by two transverse walls into three 

 cells ; the lowest or basal cell undergoes a few divisions, 



FIG. 34. Ripe antheridium, 

 showing spermatozoids 

 escaping. Magnified 350 

 diameters. (After Luers- 

 sen.) 



