PROTOZOA IN CARCINOMA. 



199 



their behaviour within the cell, and possibly also external to it, to 

 well-known species of sporozoa recognized as parasitic in animals, 

 all point forcibly to the conclusion that these bodies, though not 

 necessarily coccidia, are nevertheless protozoa, and are parasitic in 

 cancerous epithelium. 



Fig. 55. — a, b, Groups of cells containing intracellular parasites magni- 

 fied about 1,000 ; c, cancer alveolus from edge of rapidly growing 

 carcinoma of breast, showing numerous parasites magnified about 

 400. 



Methods. 

 At an early period of this investigation it occurred very natu- 

 rally to me that cancers had been probably the most frequently 

 investigated, from the histological standpoint, of all abnormal 

 tissues, and yet these bodies had not been described. I examined 

 many old specimens of cancers prepared by myself in this labor- 

 atory for an investigation on totally different lines, and I also 

 examined a number of excellent preparations kindly lent me by a 

 friend, and prepared some years ago, when the question of para- 

 sitism was not being discussed ; in none of them could I obtain 

 satisfactory evidence of the parasite under consideration. The 

 cancers from which the preparations were made were hardened by 



