Jan., 1910.] 
Monochytrium, a New Genus. 
47 
similar granules found in the cytoplasm of many species of 
Synchytrium. 
Resting spores and zoosporangia are likewise entirely similar 
in their relations to the host cell. As already indicated the 
parasites in their first stages lie imbedded in the cytoplasm of the 
host cell. As they grow older they continue to be surrounded 
by a more or less definite layer of host cytoplasm but soon estab- 
lish definite relations with the host nucleus also which becomes so 
appressed against the parasite as to be markedly deformed 
(Figs. 8, 11, 15). There is no indication, however, that the 
immediate injury to the nucleus is very great. Though death is 
the ultimate result to the host cell the relations of parasite and 
host appear to be to a certain extent mutualistic. The host 
nucleus maintains its finer structure and staining reaction 
unchanged to the end and gives no indication of such abnormal 
behavior as Von Gutenberg, Kusano and others have reported in 
the nuclei of the host cells surrounding the galls of Synchytrium. 
The presence of the parasite causes some hypertrophy of the host 
cell which gradually enlarges to dimensions considerably in 
excess of its original size (Cf. Figs. 8, 13, with Figs. 12, 18). 
The enlargement is however very seldom sufficiently great to cause 
galls such as occur in Synchytrium. For the most part the 
hypertrophied cells find room not by swelling out from the surface 
of the host but by pushing aside the adjacent cells (Figs. 1, 16). 
These compressed cells are however, only slightly injured con- 
sidering the degree to which they are distorted (cf. Fig. 2 which 
shows a cell lying adjacent to a large zoosporangium and dis- 
torted by it.) There is surprisingly little of the disorganization 
of the tissues which is usually met with in such cases but the 
nuclei and chloroplasts of the affected cells retain their char- 
acteristic form and staining reaction even when the cell walls are 
so crowded that the outlines of the individual cells are no longer 
discernible as in cases like Fig. 16. 
The size which is attained before the active life is completed 
and encystment takes place varies from 30 to 50 ft depending 
probably on the amount of nutriment available for the parasite. 
When it first appears (Fig. 11) the wall of the resting spore is a 
thin transparent membrane secreted around the periphery of the 
parasite. When older it becomes a thick yellow wall (Fig. 12) 
which is homogeneous, one layered and smooth on the outer 
surface except for irregular roughenings due apparently to the 
adherent debris from the contents of the host cell. The spore 
wall is certainly not composed of cellulose; at no stage in its 
formation does it take the stain as do the walls of the host or the 
three layered cellulose walls of the resting spores of Rhodochvt- 
rium which are found together with it in the same slides. Its 
