lOO 



xWOSSES AND FERNS 



CHAP. 



and a third cell is cut off before the separation of the central- 

 part of the antheridium from the wall is complete. It is 

 possible, too, that in Porella this may be sometimes the case. 

 The antheridium in cross-section at this stage shows two 

 perfectly symmetrical halves (Fig. 45, A). The two central 

 cells form a rhomboid surrounded by six cells, the first of the 

 primary peripheral cells being in each case divided into two. 

 The divisions proceed rapidly in both the central cells and in 

 the peripheral ones. In the latter they are for a long time 



Fig. 44. — Porella Bolanderi (Aujt.). Successive stages of the young antheridium in median 



longitudinal section, X6oc. 



always radial, so that the wall remains but one cell thick ; but 

 as the antheridium approaches maturity periclinal walls also 

 form in the lower part, which thus becomes double, and at 

 points even three cells thick. After the division of each 

 primary central cell into equal quadrants, a series of curved 

 walls intersecting the inner walls of the peripheral cells arise, 

 and then periclinal walls (Fig. 45, C), but beyond this no 

 definite succession of walls could be traced. 



The development of the spermatozoids is the same as in other 

 Liverworts. The slender body shows about two complete coils ; 



