CELL INCLUSION DISEASES 293 



CHLAMYDOZOA 



These organisms are generally considered as being protozoal in 

 nature and as a rule belong to the filterable viruses, which is the desig- 

 nation for the infectious principles of those diseases, in which filtration 

 of defibrinated blood or serum through a Berkefeld filter capable of 

 holding back so small an organism as the M. melitensis, does not pre- 

 vent the infection being transmitted when introduced by the proper 

 atrium of infection. The Chlamydozoa are also characterized by the 

 occurrence of "cell inclusions." 



The best known infections of this group of diseases in man are smallpox, vaccinia, 

 rabies, trachoma, molluscum contagiosum, and foot and mouth disease. There are 

 many such infections in other animals. The cell inclusions are regarded as prod- 

 ucts of cellular reaction to a virus which is more or less impossible of demonstra- 

 tion. The discovery of exceedingly minute granules in some of these diseases, as 

 in variola and trachoma, has suggested that, as a reaction to the invasion by such 

 a granule, the cell throws an eveloping mantle about the invading particle. To 

 designate this we use the name Chlamydozoa. 



The generic name Cytorrhyctes has been applied to certain of these viruses, thus 

 C. vaccinia develops within the epithelial cells of stratified epithelium. In vaccinia, 

 Councilman and his colleagues consider that the development only takes place in 

 the cytoplasm of the cell. In variola, however, the developmental cycle affects the 

 nucleus. 



Cytorrhyctes luis, reported as the cause of syphilis, sporulates in the blood-vessels 

 and in the connective tissue, not in epithelial cells. 



Cytorrhyctes scarlatina was reported by Mallory to have been found in the skin 

 in four cases of scarlet fever. 



