XIX] PROTOZOA CAUSING DISEASE 515 



command universal and respectful attention. We may differ 

 from him, and may hold that his generalisations, notably 

 with reference to the same kind of parasitism in variola, 

 vaccinia, varicella, herpes, variola ovina, and in other 

 vesicular diseases, are by no means satisfactorily established 

 by the evidence he adduces ; nevertheless he makes a 

 genuine scientific and systematised attempt at throwing light 

 on what is shrouded in darkness, and what is considerably 

 complicated by the many less extensive investigations and 

 somewhat hasty assertions of a great number of young 

 pathologists. 



Omitting Pfeififer's studies of the nature, character, and 

 distribution of coccidia, klossia, and eimeria, and of the 

 sporidia (myxo-, sarco-, and micro-sporidia), let us turn to his 

 observations on amoebo-sporidia in cancer in the human 

 subject. According to him the parasite of cancer is found 

 either within the epithelial cells in the form of an intra- 

 cellular encysted spore, or around the epithelial cells as a 

 free and growing cell-like germ which, when enlarging, 

 resembles a nucleated protoplasmic cell ; such cells as are 

 always found numerously infiltrating the connective tissue 

 around the true cancer epithelial masses. That is to say 

 Pfeififer considers the various intracellular bodies as spores, 

 and the leucocytes infiltrating the connective tissue as the 

 growing cancer parasites. Views of this kind, which, on the 

 one hand, cannot be accepted as based on anything like 

 evidence, but rather as a sort of ipse dixit, cannot, on the 

 other hand, be directly disposed of. In just the same way 

 it is open to any one to affirm that the white blood cells 

 found in inflammation, &C., are amoebo-sporidia, though 

 other persons may prefer to call them inflammatory cells, 

 exudation cells, or leucocytes. They all are, whatever we 

 call them, living independent organisms which grow and 



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