20 American Quarterly Microscopical Journal. 



quite a plenteous mycelium. It is known that Achlya prolifera 

 troubles the roe of fishes in some breeding-houses, causing much 

 loss ; also that forms of Saprolegna frequently attack fishes kept 

 in aquaria, a good example of which is the following : 



On August 31st, a number of fishes caught by means of a net, 

 were placed in the University aquarium ; on September 2d, 

 some of the perch and sun-fish were attacked by this fungus, 

 appearing at a little distance as if covered by a delicate veil, 

 and the next morning died, when it was seen that the plant had 

 formed a mat of mycelium over the whole animal. At another 

 time some specimens with a small amount of the matrix were 

 carefully removed and placed in distilled water, the result was 

 growth equal to that which had taken place on those left in 

 their normal condition ; this can not be considered very satis- 

 factory however, for the organic elements from the decompos- 

 ing flesh would enter into the water, and thus tend to vitiate 

 the experiment. 



An experiment touching the point of assimilation was made 

 as follows : a turtle which had died after being partly infested 

 with Achlya racmosa, was placed in a dark closet for three days. 

 The result was a very decided increase in growth, for, when 



DESCRIPTION OF PLATE IV. 

 Fig. I. Saprolegnia sp. natural size. 

 Fig. 2. Tip of growing filament. 



Fig. 3. Tip of filament showing the aggregation of granules, and formation 

 of the sporangium. 



Fig. 4. Segmentation of the contents of the sporangium. 



Fig. 5. Sporangium with zoo<;pores formed. 



Fig. 6. Zoospores passing out. 



Fig. 7. Filament growing up in old sporangium. 



Fig. 8. Another form of Saprolegnia showing zoospores held in old sacs. 



Figs. 9-1 1. Zoospores at rest and germinated. 



Figs. 12-18. Showing rejuvinescence of zoospores. 



Figs. 19, 20. Germination of same. 



DESCRIPTION OF PLATE V. 



Fig. I. Second sporangium formed on the same filament (350 diameters). 



Fig. 2. Terminal portion of a filament from a triton. 



Fig. 3. Growing filament magnified 200 diameters. 



Fig. 4. The same one hour later. 



Fig. 5. The same three hours later. 



Fig. 6. A late sporangium of Saprolegnia sp. from a triton. 



Fig. 7. Similar sporangia opening through longer tubes. 



