212 MONOSTROMA, ULVA, AND NITELLA I-ESS. 



As we have seen, the spermary (Fig. 44, g, spy) is a 

 globular, orange coloured body attached to a leaf by a short 

 stalk. Its wall is formed of eight pieces or shields, which 

 fit against one another by toothed edges, so that the entire 

 spermary may be compared to an orange in which an equa- 

 torial incision and two meridional incisions at right angles 

 to one another have been made through the rind, dividing 



Fig. 46. — A, diagrammatic vertical section of the spermary of Nitella, 

 showing the stalk {stk), four of the eight shields {sh), each bearing on 

 its inner face a handle {hii), to which is attached a head-cell (hd) : each 

 head-cell bears six secondary head-cells (hd'), to each of which four 

 spermatic filaments (sp. f.) are attached. 



B, one of the proximal shields {sh), with handle {hn), head-cell (hd), 

 secondary head-cells (hd'), and spermatic filaments (sp. f.). 



c, a single sperm, 



d', d% d*, three stages in the development of the spermary. 



(c, after Howes.) 



it into eight triangular pieces. Strictly speaking, however, 

 only the four distal shields are triangular : the four proximal 

 ones have each its lower angle truncated by the insertion of 

 the stalk, so that they are actually four-sided. 



Each shield (Fig. 46, a and B, sK) is a single concavo- 

 convex cell having on its inner surface numerous orange- 

 coloured chromatophores : owing to the disposition of these 



