170 PROTISTS AND DISEASE 



from the pycno- to the chasmatoplasson state with the 

 appearance of chromatin, repeating stages of the thistle- 

 Synchytrium previous to its subdivision into zoospores. 

 Such forms as those in Fig. 48, 1, are hard to find because 

 parasites as they mature fall off with their host-cells. In 

 some of the elements of Borrel's drawings, e.g. Fig. 48, 2, 

 beside remains of unchanged dense substance are definite 

 small nuclei. It must surely be obvious that bodies capable 

 of producing nuclei from a previously akaryote state have as 

 much claim to be regarded as representing organisms as 

 others which have nuclei all the time. This has been the 

 basis of my position since 1892 when I found evidence of 

 new nucleus-formation in the olpidiiform bodies in cysts of 

 the ureter and in cancer. 



Cytoryctes the cause of vaccinia. Once the Cytoryctes 

 is recognised as a parasite its pathogenic quality cannot be 

 doubted by any who have made a long and careful study 

 of infected corneas on successive days. 



Borrel ascribed them to leucocytes, but his own careful 

 drawing, Fig. 48, 2, a, suffices to negative this explanation. 

 His words, " Pour caracteriser un protozoaire il faut un 

 noyau," show that, as it was with the rest of us at that 

 time, the possibility of parasites other than protozoa had not 

 occurred to him. 



In his many studies of variola and vaccinia L. Pfeiffer 

 was also handicapped and his work frustrated by the fatal 

 protozoon-idea. The likeness of Cytoryctes to some stages 



