are there called scuta. They separate when mature at the lines of 

 union and have thus been called valves. When immature they are 

 filled with green chlorophyll, but when approaching maturity they 

 become as a rule brilliant red. (In Nitella megacarpa growing in 

 deep water in Litchfield Lake, the Antheridia never become more 

 colored than a pale gold. ) The outermost layer, however, has no 

 granules and forms a 

 transparent zone about 

 the sphere, see Fig. 39, 

 "A" (N. flexilis). The 

 sides of these scuta cells 

 begin to exhibit folds 

 very early ; these folds 

 look like rays extending 

 inward. The cells of 

 the second layer do not 

 increase in size in the di- 

 rection of the periphery, 

 but in the direction of the 

 radius, and become some- 

 what cylindrical in shape; 

 they are attached to the 

 centres of the superficial 

 scutiB (where there is a 

 circular space free from 

 folds), and as the spheri- 

 cal body increases in 

 size spaces are left be- 

 tween them. These cells 

 are called manubria. 

 Each manubrium bears 

 on its inner extremity one Fig. 39- 



of the innermost series of cells, a roundish cell called the capitulum. 

 These capitula are crowded together in the centre of the Anther- 

 idium, and each capitulum incloses about six small cells, from each 

 of which grow three to five long, oscillatoria-like cells, which are 

 divided by one or two hundred septa. Each cell of these threads 

 contains a spermatozoid. (Fig. 39, "B," a manubrium, bearing on its 

 inner extremity the capitula cells with their threads. C, D, E, F, 

 represent these threads, magnified; G, the spermatozoids.) 



The growth of these threads fills all the interspaces of the Anther- 

 idium with a gelatinous mass. The spermatozoid is formed 



