218 



SEAWEEDS 



The latter cells nourish the growing cystocarp fruits, 

 and when these are fully formed, the contents become 

 very sparse. 



In describing the development of the cystocarps 



FIG. W.Callophyllis obtusifolia. a, cystocarp in sectron ; 6, carpospores. 

 Highly magnified. (After J. B. Carruthers.) 



of Callophyllis, Mr. John Carruthers says : " About 

 the same time as the spore-clusters are beginning 

 to develop, a further thickening of the cortex on 

 both sides of the fruit commences. At one side of 



