400 



MOSSES AND FERNS 



CHAP. 



but finally, with the sporangium wall, is completely dissolved, 

 and the spores set free. 



The Microspores and Male ProtJiallium 



The microspores of M. vestita (Fig. 207) are globular cells 

 about .075 mm. in diameter. The outer wall is colourless and 



Fig. 207. — Ma?-silia vestita. (Hook and Grev.). Germination of the microspores, X450; x^ 



vegetative prothallial cell ; m, basal antheridial cell ; /, peripheral antheridial cells ; A, an 



ungerminated spore, ventral aspect ; B, section of a similar one — all longitudinal sections 



except E and F, which are transverse. In these the two groups of sperm cells are separated by a 

 large sterile cell. 



sufficiently transparent to allow the contents to be dimly seen. 

 Lying close to the wall are numerous distinct starch granules, 

 and in the centre the nucleus is vaguely discernible. Sections 

 through the ungerminated spore show that the wall is thick, 

 with an inner cellulose endospore, outside of which are the 



