CHARACE.E. 



^«5 



five cells form the framework of the globule. Each head bears in the centre 

 six smaller cells (secondary heads), and from these grow four long slender 

 whip-shaped filaments, which, being coiled round and round, fill up the interior 

 of the globule (Fig. 205, B). Each of these filaments (the number of which 

 amounts to about 200) again consists of a row of small disc-shaped cells (Fig. 205, 

 D, F, F), numbering from 100 to 200. In each of these 20,000 to 40,000 



Fig 206. — Nitella flexilis ; A fertile branch (natural size) ; 

 i internodc, 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 young nucules S; a a globule ; C older leaf with two 

 leaflets, a ripe globule a, and two unripe nucules S ; D a 

 lialf-ripe nucule more strongly magnified. 



Fig. 2o%.—.\i(ella Jltxitis; A an almost ripe giolniie at the end of the primary leaf, by its side two lateral leaflets, i neutral 

 lines ; the arrows indicate the direction of the currents of protoplasm ; R a manubrium with its head and the whip-shaped filaments, 

 in which the antherozoids arise ; C end of one of the you/ig filaments ; D middle part of an older one ; E of one still older ; F ripe 

 antheridial filament with antherozoids C (C — G X 550). 



cells is formed an antherozoid, a slender spiral thread, thickened behind, and bearing 

 at its pointe'd end two long fine cilia (Fig. 205, G). When perfectly ripe, the eight 

 shields fall apart, their spherical curvature becoming diminished ; the antherozoids 

 leave their mother-cells and move about in the water. This breaking up appears 

 generally to happen in the morning, and the antherozoids are in motion for some 

 hours, till evening. 



The mature Nucule, when ready for fertilisation, is a longer or shorter prolate 

 spheroid ; it is placed upon a short pedicel, visible externally only in Nitella, and con^ 

 sists of an axial row of cells, closely surrounded by five tubes which are coiled round 

 it spirally. The whole must be considered as a metamorphosed shoot. The pedicel 

 corresponds to the lower internode of a shoot; it bears a short nodal cell, from 

 which the five enveloping tubes spring as like a whorl of leaves. Above the 



