Jan., 1910.] Monochytrium, a New Genus. 47 



similar granules found in the cytoplasm of many species of 

 S^mchytrium. 



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 injur}^ 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 graduallv 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 

 hvpertrophied 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 bv it.) There is surprisingly little of the disorganization 

 of the tissues which is usualty met w^ith 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/( 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 peripherv of the 

 parasite. AVhen older it becomes a thick yellow wall (Fig. 12) 

 which is homogeneous, one lavered 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 Rhodochyt- 

 rium which are found together with it in the same slides. Its 



