280 GENERAL MORPHOLOGY OF PLANTS 



and spores mixed in a single spore case. In Mucor mucedo 

 they are separated before the formation of the germ sporangium, 

 so that the spores in one germ sporangium from a single zygospore 

 are all + while in another they are all . 



The Water Molds. 



423. The water mold. These fungi grow on dead insects or 

 other animals in the water, or even on dead plant parts. They 

 are very common on dead insects, and sometimes are seen grow- 



Fig. 224. 



Sporangia of Saprolegnia, one with zoospores escaping and passing through the first swarm- 

 ing period. Below, passing through second swarming period and then germinating. 



ing on living but weakened fish and other aquatic animals. 

 They are easily obtained by collecting algae with some of the ditch 

 or pond water in which they grow, and throwing dead flies into it. 

 The mycelium grows through the body of the fly, and then long 

 white threads radiate out in the water all around the insect. The 

 mycelium is coarsely granular, vacuolate, and continuous. 



