VI.] STONEWORTS. 51 



7. The structure of these threads; each consists 

 of a single row of cells, containing in unripe 

 specimens nucleated protoplasm ; in older spa-- 

 cimens each contains a coiled-up antherozooid. 



b. The anther ozooids. 



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 anthero- 

 zooids. 



[Sometimes Chara cannot be obtained, wlien Nitella, 

 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, ia the commoner species, 

 the plant is not hardened by calcareous deposit ; the 

 branches arise, not OTie from a whorl of leaves, but two ; 

 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 

 examine it in water with a high power. Note 

 the superficial layer of protoplasm in which the 

 chlorophyll lies; it is stationary: focus through 

 this layer and examine the deeper one; note 

 the currents in it, marked by the granules they 

 carry along : their direction ; in the long axis 

 of the cell, up one side and down the other, 

 the boundary of the two currents being marked 



4—2 



