144 



MOSSES AND FERNS 



CHAP. 



with, and some of these are shown in the figures. V^ery 

 commonly a second cell is cut off by an oblique wall from the 

 germ tube subsequent to the first transverse wall, but this does 

 not, at least in the early stages, develop into a rhizoid, the 

 first rhizoid being met with only after the young plant has 

 become a cell body of considerable size (Fig. yy). 



Whether the young plant regularly grows from 2j single 

 apical cell is difficult to say, but it seems probable, and numerous 

 forms like Fig. 76, B were encountered where there certainly 

 seemed to be a two-sided apical cell, such as occurs so often in 



Fig. 76. — Anthoceros fusiformis. Germination of the spores, X250. A shows a form 

 with very long germ tube; in B there seems to be a definite apical cell; Fig. D, 

 2, is an apical view of D, i. 



Other Hepaticse. At a later stage (Fig. 77, B) a single apical 

 cell of the form found in the mature thallus is unmistakablv 

 present. By this time the marginal lobes that give this species 

 its peculiar crimped appearance begin to develop. They arise 

 close to the growing point, and grow rapidly beyond it, but do 

 not show any definite apical growth. The plant at this stage 

 has a striking resemblance to the prothallium of Eqiiisctiun. 

 With the appearance of the marginal lobes, the first of the 

 mucilage slits appears upon the vental surface (Fig. yy), and 

 from time to time surface cells grow out into the delicate 



