440 ELEMENTARY BIOLOGY. [CHAP. 



larly from the inner surface of each ; the 

 roundish cell (capitulum) on the inner end of 

 the manubrium ; the six secondary capitula 

 attached to the capitulum ; the thread-like 

 filaments (usually four) proceeding from each 

 of the secondary capitula. 



y. The structure of these threads; each consists 

 of a single row of cells, containing in unripe 

 specimens nucleated protoplasm ; in older 

 specimens each contains a coiled-up spermato- 

 zoid. 



h. The spermatozoids (or antlierozoids). 



a. Their form and structure ; thickened at one 

 end and granular; tapering off gradually to- 

 wards the other end, which is hyaline and 

 has two long cilia attached to it. 



^. The movements in water of ripe spermato- 

 zoids. 



[Sometimes Chara cannot be obtained, when Ni- 

 tella, another genus of the same Natural Order, and 

 of similar habit and structure, can. Nearly all the 

 points above described for Chara can be made out 

 in Nitella, with the following differences : the cortical 

 cells of the stem and leaves are absent, and, in the 

 commoner species, the plant is not hardened by cal- 

 careous deposit ; the branches arise, not one from a 

 whorl of leaves, but two j and the five twisted cells of 

 the spore-fruit are each capped by two small cells, 

 instead of one.] 



C. Protoplasmic movements in vegetable cells. 



a. Chara. Take a vigorous -looking fresh Chara or 

 Nitella cell (say the terminal cell of a leaf), and 



