222 



RHODOPHYCEAE 



which are rich in protoplasm, whilst the sterile envelope of the 

 cystocarp arises from the third cell. 



6 6 6 6 6 



Fig. 145. Scinaia furcellata. A, carpogonial branch ( x 700). B, fertilized carpo- 

 gonium. C, cystocarp ( x 195). D, plant ( x ^). E, antheridia ( x 700). F, young 

 carpogonial branch ( x 425). G, young cystocarp ( x 232). H, undifferentiated 

 threads at apex of thallus ( x 425). I, monospores and a hair ( x 340). J, dif- 

 ferentiated cortex ( X 429). K, life-cycle diagram. (C, after Setchell; D, original; 

 rest after Svedelius.) 



It is now certain that in the related genus Chaetangium, and 

 probably also in Galaxaura, the wall of the cystocarp arises from 

 the cell containing the fertilized nucleus, so that it is composed of 

 fertile gonimoblasts and not sterile tissue. The fertilized nucleus in 



