350 THE president's ADDRESS; 



cell -enclosure known in the case of small-pox and vaccinia as 

 a Gnarnieri's body, from its discoverer, who regarded it as the 

 true parasite and named it Cytoryctes ; according to the most 

 recent investigations, however, the Guarnieri's bodies, and similar 

 bodies in other diseases, are merely extrusions from the nucleus 

 enveloping the true parasites that is to say, the Chlamydozoa. 

 Finally the Guarnieri's body breaks up, the cell becomes full of 

 initial corpuscles which divide up into numerous elementary 

 corpuscles, and the cycle is complete. 



In all this cycle of development the Chlamydozoa multiply 

 actively by simple division into two, and in this process of 

 division there are some noteworthy features. The minute 

 organism is not constricted simply into two, like a bacterium, 

 but becomes dumb-bell-shaped, the two daughter-individuals as 

 they separate being connected by a thread which is drawn out 

 until it snaps. The division recalls that of a centrosome in an 

 ordinary cell. I interpret this to mean that the minute body 

 of a Chlamydozoon is not limited by a membrane like that of 

 a bacterium, but is naked and of a fluid nature ; consequently, 

 when division takes place, the viscous body is drawn out in the 

 manner seen and described. 



Thus to sum up briefly the characteristics of the Chlamydozoa : 

 they are organisms so minute as to be barely visible, in some 

 cases, perhaps, quite invisible, with the highest powers of the 

 microscope, and to be able to pass through filters which bacteria 

 cannot pass. When seen, they present themselves simply as 

 tiny specks of chromatin, in which no structure can be made 

 out, and their mode of division indicates a structure simpler 

 than that of bacteria, in that at least a membrane enclosing 

 the body appears to be lacking. In all cases known at present 

 they occur as parasites of cells in which they produce character- 

 istic secondary growths or extrusions from the nucleus ; although 

 first known as causing diseases of man and the higher animals, 

 they are now stated to occur also as parasites of Protozoa for 

 example, of Amoeba and Paramecium and quite recently the 

 opinion has been expressed that the elusive, and perhaps alto- 

 gether mythical, cancer-parasite is to be referred to the Chlamy- 

 dozoa.* To these various characteristics it should be added that 



* Awerinzew, S., " Zur Frage liber die Krebsgeschwlilste," Centralhl. 

 Bakt. Parasitenhnnde (Abt. I.), Ivi. pp. 506-508, 3 text-figs. 



