THE PATHOGENIC RHIZOPODA 



311 



to the toxins, infective material, etc., of the developing pustule, or pos- 

 sibly to ill preservation of the tissues. They are characteristic of the 

 later pustules, and their vacuolated appearance may be ascribed to the 

 same causes as that which produces poorly fixed and stained amebse, 

 or poorly stained Negri bodies. In the latter the better technique 

 of recent methods has shown that what appear as vacuoles in the 

 photographs are actually chromatin fragments (see Fig. 125), and by 

 analogy I would prophesy that when better methods of fixing and 

 staining the intranuclear form of cytoryctes are devised, a similar 

 chromatin distribution will be discovered. The tissues, such as we 

 worked upon four years ago, show many cellular structures like those of 

 the well-fixed and stained Negri body (compare Figs. 121, 122, 124 and 

 125), and although these were regarded formerly as aberrant forms of 

 the sporoblast structures, many of them were figured and described. 



FIG. 125 









A large cytoplasmic form of Cytoryctes variolse. 



As with neuroryctes, further study with better methods must be 

 undertaken to complete the life history of cytoryctes; the important 

 sexual stages must be found, a hint to this end being given by the 

 changed nuclear phenomena of the intranuclear form (see difference 

 in nuclear processes of vegetative and sexual phases of entameba). 



In this same category, finally, must be placed the interesting organ- 

 isms discovered by Mallory ('04) in the skin cells of scarlet fever 

 victims, and named by him Cyclasterion scarlatinalis (Plate IV). Also 

 the curious structures described by Prowazek in trachoma, forms 



