BRYOFHYTES 



105 



is a single layer of sterile cells as a wall about the arche- 

 sporium, which is composed of all the remaining cells of the 

 upper half (Fig. 86, B). It will be noted that the sterile 

 tissue in this sporogonium has encroached upon the arche- 

 sporium, which is restricted to one half of the body. In 

 this case the archesporium has the form of a hemisphere. 



In another liverwort (Jungermannia) the archesporium 

 is still more restricted (Fig. 87). The sterile tissue is organ- 



FIG. 87. Diagrammatic section of spo- 

 rogonium of a Jungermannia form, 

 showing differentiation into foot, 

 seta, and capsule, the archesporium 

 restricted to upper part of sporogo- 

 nium. After GOKBEL. 



FIG. 88. Section through sporogonium of 

 Sphagnum, showing capsule (k) with 

 old archejronium neck (ah), calyptra (ca), 

 dome-shaped mass of sporogenous tissue 

 (spo), and columella (co), also the bulb- 

 ous foot (spf) imbedded in the pseudo- 

 podium (ps). After SCHIMPBB. 



ized into a foot and a seta, and the archesporium is a com- 

 paratively small mass of cells in the upper part of the 

 sporogonium. 



In another liverwort (Anthoceros) the sterile tissue or- 

 ganizes foot and seta, and the archesporium is still more 

 restricted (Fig. 86, D). Instead of a solid hemispheric.il 



