472 THE PROTOZOA 



4. The foregoing sceptical phase has been succeeded by the positive 

 belief that the true parasitic organism in these diseases consists of 

 certain minute bodies the Chlamydozoa or strongyloplasms.* 



The chief characteristics of the Chlamydozoa, according to 

 Prowazek and Lipschiitz (913), are, first, their minute size, smaller 

 than any bacteria hitherto known, enabling them to pass the 

 ordinary bacterial filters ; secondly, that they develop within cells, 

 in the cytoplasm or nucleus, and produce characteristic reaction- 

 products and enclosures of the cell (their position within the cell 

 is not the result of phagocytosis) ; thirdly, that they pass through 

 a series of developmental stages, and are specially characterized by 

 their mode of division, which is not a simple process of splitting, 

 as in bacteria, but is effected with formation of a dumb-bell-shaped 

 figure, as in the division of a centriole. Two dots are seen con- 

 nected by a fine line like a centrodesmose, which becomes drawn out 

 until it snaps across the middle, and its two halves are then re- 

 tracted into the body. Chlamydozoa have not yet been grown 

 successfully in cultures, but infections can be produced with pure 

 colloid- filtrates, free from bacteria, but containing the minute 

 bodies themselves. They are characteristically parasites of epi- 

 blastic cells and tissues. 



As an example of the development of a chlamydozoon may be 

 taken that of the vaccine- virus, which, according to Prowazek (913) 

 and Hartmann (909), is briefly as follows : 



1. The infection begins and ends with numerous "elementary 

 corpuscles " (gemmules of Calkins ?), which occur both within and 

 amongst the cells. They are very minute, and can pass bacterial filters. 



2. Within the cells the elementary corpuscles grow into the 

 larger " initial bodies." 



3. The infected cell extrudes nucleolar substance plastin from 

 its nucleus, which envelops the parasites as in a mantle (hence the 

 name Chlamydozoa, from x^ a /*vs, a mantle), thus producing in the 

 case of vaccine the characteristic Guarnieri's bodies, in which the 

 parasites multiply. It is this mantle of nucleolar substance, 

 apparently, which represents the " cytoplasm " of Cytoryctes, as 

 described by Calkins. 



* The name Chlamydozoa, as denoting a class of microscopic organisms, must 

 on no account be confused with the names Cytoryctes, Neuroryctes, etc., which 

 represent the generic names of the supposed parasites of variola and rabies re- 

 spectively. To those who regard Cytoryctes, etc., as true organisms, the Chlamydo- 

 zoa are merely chromidia or dots of chromatin in the body of the parasite ; to 

 those who believe in the Chlamydozoa as complete organisms, Cytoryctes, etc., 

 are cell-inclusions or degeneration-products of the nucleus. The conceptions 

 implied in the words Chlamydozoa and Cytoryctes respectively are antagonistic 

 and mutually destructive ; if the one is a reality, the other is non-existent. It is 

 altogether incorrect to speak of Cytoryctes, Neuroryctes, etc., as genera of Chlamv- 

 dozoa. 



