BRYOPHYTES 



109 



later the sporogenous tissue becomes two layers of cells. The outer layer 



of the amphithecium develops a capsule wall of four or more layers, the 



outermost one being the epidermal layer, 



consisting of elongated narrow cells and 



containing stomata similar to those of vas- 



cular plants. The stomata are related to 



the fact that the wall layers beneath the epi- 



dermis are chlorophyll tissue, giving to the 



sporophyte the ability to manufacture food. 



The intermediate zone adds continuously 



new capsule regions below; therefore in a 



longitudinal section of a capsule the whole 



sporogenous series may be seen, from one- 



layered sporogenous tissue below, through 



two-layered sporogenous tissue, mother cells, 



and tetrads, to mature spores above (fig. 



241). The capsule dehisces by splitting into 



two valves, which separate downwards as 



the spores mature, leaving the spores ex- 



posed upon the columella (fig. 239). 



In many cases some of the sporogenous 

 cells do not form spores. These sterile 

 groups of cells break up the continuous 

 mass of sporogenous cells into more or less 



', mi i 11 FIG. 241. Antkoceros: longi- 



separated groups. This tendency to break tudinal section th rou gh portions 



up the sporogenous tissue into separate of a sporophyte, showing bulbous 



smaller masses by intervening sterile tissue foot embedded in the gameto- 

 / ,.,., - , phvte; above the foot is the zone 



is an important fact, which will be referred of actively divid;ng ce u s e i onga t- 

 to later. These sterilized and somewhat ing the sporophyw; the base of 



modified sporogenous cells are called ihe ca P sule shows the 



. . , , if ,.~ L e chlorophyll tissue, the sporoge- 



elaters, but they are different from those nous tissue (at first one layer 



found among Marchantiales. This green of cells, then dividing to form 



sporophyte, with its sterile and elongating two lavers )' and the columella ; 



... section from middle region show- 



axis, and its sporogenous tissue broken up ing sp0 re mother cells with sterile 



into Smaller masses, is Very suggestive of a cells between; section from upper 



possible relation to the completely inde- re s ion showin g tetrads and 



, , ... . i , sterilized sporogenous cells. 



pendent sporophyte of the ptendophytes. 



Conclusions. Among the Anthocerotales there is a remarkable 

 association of a primitive type of gametophyte with a highly developed 



