I30 



MOSSES AND FERNS 



CHAP. 



stalk from the upper part is secondary; indeed in the earhest 

 stages it is difficult to tell whether these longitudinal divisions 

 will result in four vSeparate antheridia or are the first division 

 walls in a single one. Secondary antheridia arise later by 

 budding from the base of the older ones, so that in the more 

 advanced conditions the antheridial group consists of a varying 

 number, in very different stages of development (Fig. 68, A). 



A /->^.--<^>N C, 



I D 



Fig. 68. — Anthoceros fusiformis. Development of the antheridium ; D, E, drawn from 

 living specimens, the others microtome sections; D, i, shows the single chloroplast 

 in each of the wall cells, and the secondary antheridium {s) budding out from 

 its base; 2 is an optical section of the same; E, surface view of full-grown antherid- 

 ium; F, cross-section of a younger one. Figs. A, E X225, the others X4S0. 



After the first transverse walls by which the stalk is separated, 

 the next division in each of the upper cells is parallel to it, so 

 that the body of the antheridium is composed of nearly equal 

 octant cells. Then by a periclinal wall each of these eight cells 

 is divided into an inner and an outer cell, and the eight central 

 ones then give rise to the sperm cells, and the outer ones to 

 the wall. The four stalk cells by repeated transverse divisions 

 form the four-rowed stalk found in the ripe antheridium. The 

 uppermost tier of the stalk has its cells also divided by vertical 

 walls and forms the basal part of the antheridium wall. The 

 transverse and vertical division walls in the central cells alter- 

 nate with great regularity, so that there is little displacement 

 of the cells, and up to the time of the separation of the sperm 



