THE ANTHOCEROTE^ 



129 



pcriclinal wall next forms, which cuts off an inner square cell 

 (Fig. 60, D). In longitudinal section these periclinal walls arc 

 seen to be concentric with the outer walls of the cells, and to 

 strike the median and quadrant walls at some distance below 

 the apex of the sporogonium so as to completely enclose the 

 central cells (Fig. 60, C). By the formation of these first 

 periclinal walls the separation of the columella from the wall of 



A 



Fig. 60. — A^ithoceros liezns (L.). Development of the embryo, X300; A, C, E, median longitudinal 

 sections ; B and D, successive cross-sections of embryos of about the age of A and C respecdvely. 

 In E the archesporium is differentiated. 



the capsule is completed, and this is not unlike what obtains in 

 the sporogonium of many other Hepaticje ; but an essential 

 difference must be observed. In the latter the central group 

 of cells forms the archesporium ; here these cells, as we shall 

 see, take no part in spore formation. In the lower tiers of 

 cells similar but less regular divisions occur (Fig. 60, D 2), and 

 the outer cells begin to grow out into root-like processes which 

 push down among the cells of the thallus and obviously serve 



K 



