90 



THE ALGAE 



and although no sexual fusion has been seen as yet, nevertheless 

 meiosis occurs in V. utricularis at swarmer formation. The plants 

 are therefore presumably diploid, a condition that is also character- 

 istic of most of the Siphonales. The reproductive cells may encyst 



Fig. 49 Valonia. A, young plant of V. ventricosa. B, young plant 

 of V. ultricularis ( x 1-4). C, adult plant of same, m = marginal cell. 

 D, plant of V. macrophysa ( xo-8). E, rhizoid of V. utricularis. F, 

 rhizoids from marginal cells at base of vesicle of V. ventricosa. G, 

 single marginal cell and rhizoid (r) of K. ventricosa. H, V. utricularis 

 fruiting. I, V. utricularis^ germinating swarmer. (B, D, after 



Taylor i rest after Fritsch.) 



themselves, and it has been suggested on this evidence that the 

 plant is a colonial aggregate of coenocytic individuals resulting 

 from the retention of cysts that have developed in situ. The correct- 

 ness or otherwise of this interpretation can only be obtained through 

 a better knowledge of their phylogenetic history and the repro- 

 ductive processes of other members of the group. 



REFERENCES 



General 



Chapman, V. J. (1954), Bull. Torr. Bot. Club, 81 (i), 76. 

 Egerod, L. E. (1952). Univ. Cal. Pub. Bot., 25, p. 325. 

 Feldmaruij J. (1938). Rev. Gen. Bot., 50, 57. 



Spongomorpha 



Fan, K-C. (1959). Bull. Torr. Bot. Club, 86 {i),i. 



