FUNGI: SAPROLEGNIA. 



181 



Water Moulds (Saprolegnia). 



391. The water moulds are very interesting plants to stud} 

 because they are so easy to obtain, and it is so easy to observe a 

 type of gonidium here to which we have referred in our studies 

 ofthealgse, the motile gonidium, or zoogonidiuin. (See appen- 

 dix for directions for cultivating this mould.) 



392. Appearance of the saprolegnia. In the course of a 

 few days we are quite certain to see in some of the cultures deli- 

 cate whitish threads, radiating outward from the body of the fly 

 in the water. A few threads should be examined from day to 

 day to determine the stage of the fungus. 



393. Sporangia of saprolegnia. The sporangia of saprolegnia 

 can be easily detected because they are much stouter than the 

 ordinary threads of the mycelium. Some of the threads should 

 be mounted in fresh water. Search for some of those which 



Fig. 195- 



Sporangia of saprolegnia, one showing the escape of the zoogo- 

 nidia. 



show that the protoplasm is divided up into a 

 great number of small areas, as shown in fig. 195. 

 With the low power we should watch some of the older ap- 

 pearing ones, and if after a few minutes they do not open, other 

 preparations should be made. 



