SAPROLEGNIALES 



163 



The empty polyhedral cyst walls give the emptied sporangium 

 the aspect of a net ; hence the genus name. The sporangia are 

 usually fusiform, new ones being formed in basipetal succession 



Fig. oS.^Dictyuchus sp. (a) Two successively formed sporangia, the terminal 

 one empty and showing the "cell net" structure, the second still containing the 

 spores, (b) An atypical sporangium developed from a starved hypha, showing 

 incomplete contact of adjacent spores, (c) Germination of sporangiospores 

 in situ, (d-p) A series of drawings illustrating "successive zoospore" emer- 

 gence, (d, e) Escape from sporangium. (/, g) First motUe period; spore 

 reniform and biciliate. {h) Encysted zoospore. (A;) Second emergence, 

 (m, n) Second swarming period; same type as first, (p) Final encystment and 

 germination. {After Weston 1919.) 



or by sympodial branching. It is of interest to note that they 

 frequently fall away from each other and from the hypha, and 

 he free in the water. This deciduous character of the sporangium 

 unusual in this order, though common in the next. Its 



IS 



