THE ACRASIEAE 



145 



Fig. 78. — Hydrodictyon utriculatum, a Water-net. Drawings which illustrate 

 the origin of a net from a combination of zoospores. A, a piece of a net 

 showing the, cylindrical cells of which it is composed. B, a cylindrical 

 cell with a swollen cell-wall, containing a net which has just been formed 

 from a combination of zoospores. C, a number of zoospores, which were 

 produced in a cylindrical cell like B, connected together by fine proto- 

 plasmic threads (threads not shown) and each provided with two cilia 

 (cilia of the three inner zoospores directed toward centre not shown) ; 

 the zoospores are moving about, but keeping the arrangement shown, and 

 soon they would each develop into a cylindrical cell and so form a net 

 like that in B. D, a single gamete. E, two gametes becoming fused 

 together ; F, a zygote. From G. Klebs, Die Bedingunrjen der Fortflanzung 

 bei einigen Algen und Pilzen, Jena, 1896, Fig. 4, p. 134. Magnification : 

 A and B, 120 ; C-F, 1000. 



VOL. IV. 



