84 



MOSSES AND FERNS 



CHAP. 



serve as the growing point of two shoots, which may continue 

 to grow equally, when the thallus shows a marked forking 

 {M. fiircata), or one of the branches grows more strongly than 

 the other, which is thus forced to one side and appears like a 

 lateral branch {A. pinnatijida, Fig. 38, B). 



The sexual organs in both Aneura and Metzgeria are borne 

 on short branches, which in the latter arise as ventral structures, 



A 



Fig. 34. — Anertra pinnatijida (Nees).'' A, Part of a thallus with two antheridial branches, slightly- 

 magnified ; B, an archegonial branch, X 40 ; C, cells from the margin of the archegonial branch 

 showing the oil bodies (,0), X 300. 



but in Aneura are simply ordinary branches that are checked 

 in their growth by the production of the sexual organs, and 

 not infrequently may grow out into ordinary branches after the 

 formation of the sexual organs has ceased. In A. pinnatijida 

 (Fig 34, B) archegonia and antheridia are usually produced 

 upon separate branches, but may occur together. 



The origin of the antheridia can be readily followed in sections 



