298 



THALLOPHVTES. 



placed below, in the Charx above or by the side of the antheridium. In the dioecious 

 species of course no such relation of position can exist, but the morphological signi- 

 ficance of these organs and the place of their origin are the same. We will now 

 consider the structure of these organs when they are fully developed. 



The Antheridia (Globules) are globular bodies ^ to i mm. in diameter, at first green, 

 then red. The wall consists of eight flat cells, four of which, situated around the distal 

 pole of the ball, are triangular, while the four situated around the base are quad- 

 rangular and become narrower below ; each of these cells forms a segment of the 

 shell of the ball, and are called Shields. When unripe their inner cell-wall is covered 

 with green chlorophyll-granules, which, in the ripe state, are of a red colour. Since 



FIG. x^.—Nitella flexilis. A fertile branch (natural 

 size) ; i internode, b leaves ; B upper part of a fertile leaf 

 b with the node K ; on the node are two lateral leaves n b, 

 and two very younjj carpogonia S; a an antheridium ; 

 C older leaf with two leaflets, a ripe antheridium a, and 

 two unripe carpogonia S; Da half-ripe carpogonium more 

 strongly magnified. 



Fig. 198. — Xitella Jlexilis. A an almost ripe antheridium at the end of the primai-y leaf, by it.s side two lateral leaflets, i 

 neutral lines ; the arrows indicate the direction of the currents of protoplasm ; B a manubrium with its capitulum, secondary capitula, 

 and the whip-shaped filaments, in which the antherozoids arise ; C end of one of the young filaments ; D middle part of an older 

 one ; E of one still older : F ripe antheridial filament with antherozoids G (C—G X 550). 



the outer wall is destitute of these granules, the outside of the ball appears clear 

 and transparent (Fig. 197, A). From the lateral walls several folds of the cell-wall 

 penetrate towards the middle of each shield, which gives them the appearance of being 

 lobed in a radiate manner. From the middle of the inner face of each shield a cylin- 

 drical cell projects inwards, nearly to the centre of the hollow globule; this cell 

 is called the Manubrium; at the central end of each of the eight manubria is a 

 roundish hyaline cell, the Capitulum. The flask-shaped cell which supports the antheri- 

 dium also penetrates into the interior between the four lower shields ; and these twenty- 

 five cells form the framework of the antheridium. Each capitulum bears usually 

 six smaller cells {secondary capitula), and from each of these grow four long slender 



