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 
Fic 67.—Callophyllis obtusifolia. a, cystocarp in section; b, 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 
