XIX] PROTOZOA CAUSING DISEASE 513 



within the inflamed epithelium (Strieker, Rindfleiscli, and 

 others) ; or whether, as Cohnheim and others maintained, 

 and as is now universally believed, they are immigrants into 

 the epithelium and into the epithelial cells themselves. As 

 a matter of fact, they are found easily in the epithelium in 

 gonorrhoea and in the conjunctiva in catarrhal (blennorrhceal) 

 inflammation. 



Messrs. Ruffer and Walker meeting, in cancer, with 

 vacuolated epithelial cells enclosing several leucocytes, seem 

 to assume that there has originally been a parasite within 

 each such epithelial cell, which has been eaten up by the 

 leucocytes. And in this way it could be shown that, in a 

 considerable number of instances, belief has arisen in the 

 existence of coccidia, psorosperms, and other parasitic forms 

 in cancer epithelial cells. Those enunciating such belief 

 would seem to be wanting in a clear understanding of the 

 elements of the problem with which they are concerned ; 

 for in dealing with purely morphological questions, such as 

 the presence or absence of certain bodies in the hyper- 

 trophied epithelium constituting cancer and similar chronic 

 epithelial diseases, it is obvious that a critical apprehension 

 of what appertains to cancerous epithelial new-growths and 

 to no other epithelium in health or disease is necessary as an 

 elementary condition for proper study of the subject. And 

 let me here at once say, in making this statement, that I am 

 in no way disinclined to regard molluscum contagiosum, 

 Paget's disease, and cancer as belonging to the group of in- 

 fectious diseases that are of parasitic origin ; all that I wish 

 to insist on is that many, if not most, of the assertions as 

 to coccidia, psorosperms, and similar parasites in cancer 

 and in allied diseases are not founded on admissible 

 evidence. See Mr. D'Arcy Power's demonstration ^ of some 

 '^ Journal of Pathology and Bad. viii. No, i, p. 124. 



L I. 



