1917] 
MOORE—CHLOROCHYTRIUM GLOEOPHILUM 275 
gests that possibly Chlorochytrium gloeophilum originally 
possessed a motile spore, but that owing to the habitat 
adopted, in which a ciliated spore would be unable to swim, 
the cilia were lost. It was originally assumed that the plants 
at some stage in their existence left the Rivularia, and that 
ciliated spores would afford an easy means of again establish- 
ing themselves in the gelatinous colonies. This does not seem 
to be the case, however. The Chlorochytrium cells apparently 
never give up their endophytic habit, and new colonies of 
Rivularia are infected from aplanospores contained in the 
gelatin surrounding the young filaments which increase with 
the development of the Rivularia colony. 
With the idea that possibly C. gloeophilum might occur in 
other species of Rivularia the following forms were examined 
from exsiecati: Rabenhorst, 295, В. minor; 355, В. pygmaea; 
416, R. minuta; 648, R. angulosa; 748, R. minuta; 793, R. 
Sprengeliana; 931, R. angulosa; 932, R. Lyngbyana; 975, R. 
Lenticula; 976, В. durissima; 1095, В. minuta; 1125, В. Spren- 
geliana; 1452, В. insignis; 2184, R. villosa; 2540, В. fluitans; 
2563, R. terebralis. Collins, Holden, and Setchell, 357, R. 
atra; 858, В. Biasolettiana; 260, В. nitida; 508, В. compacta; 
860, В. Biasolettiana; 1015, В. polyotis. Tilden, 166, В. Biaso- 
lettiana; 289, В. haematites; 570, В. Biasolettiana; 571, В. 
nitida. In no case was there the slightest indication of the 
presence of the endophyte. 
Specimens of the following included in the Missouri Botan- 
ical Garden Herbarium were also examined, but with negative 
results: Rivularia nitida, R. bullata, R. fluitans, R. atra, as 
well as several undetermined species. In view of the fact 
that none of these specimens showed the presence of C. gloeo- 
philum, it is interesting to note that the specimen of R. Borne- 
папа from Watch Hill Pond, Watch Hill, В. I., distributed as 
No. 157 in Collins, Holden, and Setchell’s ‘Phycotheca,’ con- 
tained an abundance of grass-green cells within the gelatinous 
matrix, which was easily recognized as C. gloeophilum. Hence 
at the only two localities thus far noted in the United States 
for R. Bornetiana, C. gloeophilum is found growing within it 
and apparently in no other species. 
