142 American Quarterly Aficroscopical Joi/nial. 



The first specimens were found upon a fiy whicli had fallen 

 into a dish of creek water. The filaments, about 5 mm. in 

 length, formed a dense mat, differing in general appearance 

 from ^'. ferax found in similar situations, by being very 

 white, when heavily in fruit, instead of light-gray. After a 

 careful examination, other flies were placed in small bottles and 

 sown with spores from the specimens found. In one day from 

 the time of sowing, growth was evident by very short filaments, 

 giving a velvety appearance to that portion of the fly on which 

 they were; in two days the fly was entirely surrounded, the 

 largest filaments having a length of about 4 mm. At the end of 

 the third day many oogonia were present, but, out of some sixty 

 noted, only three had formed gonospheres, four showed segre- 

 gation, while all the rest were dark and granular or just form- 

 ing. Good specimens for study were produced, but I could 

 not watch the development of the oogonia with sufficient care. 

 Flies were then placed in watch-glasses and sown with spores 

 from the second crop; this was repeated six times, seeding 

 each experiment with spores from the one preceding, and 

 proved to be a desirable manner of growing to permit examin- 

 ation in their natural condition. 



In all cases the fruiting took place on filaments near the sur- 

 face of the water, where the oogonia were produced in such 

 profusion as to give the mass a white and very fine granular 

 appearance. A meager growth of filaments extended below, 

 but were, in most cases, barren. When the flies sank, so as to 

 be entirely covered by water, a very small number of oogonia 

 were produced. When a young and thrifty specimen was 

 caused to sink, the production of oogonia was very materially 

 checked, and occasional sporangia were produced. Thus we 

 see that for the successful production of the sexual form, the 

 specimen must be near the surface of the water. I could not 

 see that any of the oogonia were formed above the surface, and 

 it will be seen farther on that fertilization could not be effected 

 if such were the case; so the only reason that I can assign for 

 this fact is, that the plant may have some aerial hyphae, and 

 thus need the action of air on some of its parts. When a very 

 thrifty growth took place, there was formed a light mat of an- 

 astomosing filaments just at the surface. Closer observa- 

 tions were not then made, and experiments since, to determine 

 more satisfactorily this as well as other points, have resulted in 

 the non-appearance of the fungus. 



