258 



SPOROPHYTE OF MARCHANTIA 



the center of the branches. Fertilization is effected, as in all 

 forms, by means of dews and rains which flood these organs with 

 water. After fertilization these mushroom-shaped branches elon- 

 gate, raising the sexual organs up into the air, where the anthe- 

 ridial branch assumes the form of a lobed disc, while the arche- 

 gonial branch terminates in an umbrella-like structure (Figs. 186, 

 190). Owing to the extended growth of this latter branch, the 



Fig. 191. Fig. 192. 



Fig. 191. Section of an archegonial branch similar to a, Fig. 190 — 

 ar, archegonia; in, involucre or curtain that hangs down on either side 

 of the rows of archegonia ; ac, air chambers ; th, thallns. 



Fig. 192. Section of a young antheridial branch : an, antheridia sunken 

 in cavities of the branch, which is also provided with air chambers similar 

 to those of the normal thallns. Some of the antheridia have discharged 

 their gametes, as at x. 



archegonia come to lie on the under side of the structure between 

 the finger-like outgrowths, where they are completely hidden and 

 protected by fringed curtains, the involucre, that hang down from 

 the fingers (Figs. 191, 195, A). The antheridia retain their orig- 

 inal position upon the branch, where they appear in cavities, as 

 shown in Fig. 192. 



The most important and significant departure in MarchanHa is 

 seen in the germination of the gametospore which divides into an 

 inner and outer cell as in Ricciocarpus (Fig. 193, B). The inner 

 cell, however, by a series of divisions, forms a rudimentary stalk 

 and the lower part of it, known as the foot, comes into close 



