AI.I.OMVCES 183 



After an hour they had encysted and one had sprouted. The spores arc of 

 a peculiar internal structure, resembling closely those of B. Pnngsheimii 

 as shown l)y Thaxter (1. c, pi. 3, hg. 11). Most of the protoi)!asm is at 

 the end opposite the cilia, the center is almost clear and the cilia seem to 

 e.\tend down through the clear tip to a protoplasmic mass below, as shown 

 in our fig. 5. 



On an agar plate the plant does not do well. .X few root-like threads grow out, branched 

 and with cross-walls in the older portions, and in these older portions are found resting 

 bodies or sporangia, sometimes fifteen or twenty of the latter in a row. The repro- 

 ductive bodies are sometimes found in clusters or single on short lateral stalks. 



On boiled corn agar the growth is good. The threads are about the same size as on an ant 

 but average longer, as much as 5 mm., and the protoplasm is not as dense as when 

 grown on ants. Threads at substratum as large as I02ix in diameter. Sporangia are [)ro- 

 duced better than on ants, and resting bodies are so abundant that the entire culture 

 assumes a brick dust color to the unaided eye. The resting bodies are at first dark and 

 have numerous large oil droplets. .As they get older the walls assume a yellow-brown 

 color and the contents becomes homogeneous. 



PARASITE.S OF THE \VATERMOLD.S 



The parasites of the water molds have been conveniently grouped 

 by Fischer ('92, p. 149), and we adapt the following from him with the 

 addition of two species of Olpidiopsis recently described. To Fischer 

 one may also go for the literature. We are describing more fully only 

 those species which we have had an opportunity to study in the li\-ing 

 condition. 



On hyphae of Saprolegnia: Olpidiuni Borzianum; Pseudolpidium Saprolegniae; Olpidi- 

 opsis Saprolegniac; Olpidiopsis echinata (See Petersen in Ann. 

 Myc. 8: 540. 1910); Olpidiopsis major*; Woronina polycystis; 

 Rozella septigena. 

 On hyphae of Achlya: Pseudolpidium fusiforme; Olpidiopsis minor; Olpidiopsis in- 

 dex; Rozella simiilaiis. 

 On oogonia of Saprolegnia 



and Achlya: Rhizophidium carpophilum; Rhizidiomyces apophysatus. 



On Aphanomyces: Pseudolpidium aphanomyces. 



On Rhipidium spinosum: Pleolpidium Rhipidii. 

 On Monoblepharis poly- 



morpha: Pleolpidium Monoblepharidis. 



* See Maurizio ('95), p. 15, figs. 4-9. Grows on S. ferax and 5. hypogyna. This is 

 very doubtfully distinct from 0. Saprolegniae. 



