WATER MOLD (SAPROLEGNIA) 



353 



which are not known to have a life history of the type character- 

 istic of either of the other subdivisions. Their life histories so 

 far as they are known are imperfect. 



Phycomycetes (Alga-like Fungi) 



This group, as their name suggests, resembles the Algae, but it 

 is a large assemblage of plants which vary widely in both struc- 

 ture and habit. Some of them live 

 in the water and have zoospores 

 and sex organs similar to those of 

 the Green Algae, while some have 

 lost their water habits and nearly 

 all of their algal features. There 

 are three principal orders Water 

 Molds (Saprolegniales) , Downy 

 Mildews ( Peronosporales) , and 

 True Molds (Mucorales). 



Water Molds (Saprolegniales). 

 These are the Fungi showing closest 

 affinities with the Algae. In fact, 

 if some of them had chlorophyll, 

 they could scarcely be told from 

 some of the Green Algae. They (Saprolegnia) . A, a fly affected 

 live in the water where they feed with Saprolegnia. The fuzzy ap- 

 upon the dead bodies of insects pearance of the fly is due to mi- 

 fish, and tadpoles. Sometimes they meroushyphae which project from 

 ' . . J the body of the fly. B, tips of 



attack living organisms, as the one projecting hyphae which have 



called Saprolegnia illustrates. formed zoosporangia. From .the 



Water Mold (Saprolegnia). zoosporangium at the right the 



There are several kinds of Water zoospores are escaping. C, a 



Molds, but the one called Sapro- tip of a projecting hypha bearing 



, . ' . _.. an oogonmm containing a number 



legnia, shown in Figure 304, is a ofeggs D, an oogonium and an- 



very common one. Although com- theridium, the latter of which has 



monly a saprophyte on the floating pierced the wall of the oogonium 



bodies of dead organisms, it often and thereby enabled tha sperms 



attacks and kills young fish that to reach the eggs ' 

 are confined in close quarters, on which account it is some- 

 times very destructive in fish hatcheries. This Fungus, since 



it can live on both live and dead organisms, shows that there 



FIG. 304. A Water Mold 



