PROTOZOA IN CARCINOMA. 



193 



empty. The fibrous boundary of the adenoma becomes thicker, 

 contracts, and, at length, the lesion caused by the attack of the 

 parasite heals, and its site is marked by a small concentric nodule 

 of fibrous tissue. 



(/ 



h 



Fig. 50. — a, b, Formation of crescentic spores within the daughter sphe- 

 rules, external to the host (after Balbiani) ; c^ d, sporulation within 

 the host, division of the spores into numerous crescentic segments. 

 (After photographs by Pfeiffer magnified 1,000.) 



In the small intestine, the areas of mucous membrane affected 

 show similar changes to those described ; the protozoa penetrate 

 deeply into the glands, the epithelial cells become infected, the 

 mucous membrane is thickened, and there results a hypertrophied, 

 adenomatous condition of the particular area involved. 



Inoculation Experiments. 



Before passing from this division of my subject, I wish to draw 

 attention to certain attempts which have been made to produce 

 this disease by artificial introduction of the organism. Messrs. 

 Ballance and Shattock attempted to infect certain animals by 

 means of " psorospermial material," both by subcutaneous inocu- 

 lation and intravenous injection.* Mr. D'Arcy Power, by means 

 of specially-devised methods, has sought to produce the disease 

 by the implantation of coccidia on specially irritated epithelial 

 surfaces. Dr. R. Pfeiffer has taken coccidia which have passed 

 through their cycle of development external to the body, and were 

 thus presumably in a stage capable of causing infection, and injec- 

 ted them directly into the liver and into the veins of presumably 

 healthy animals. All these experiments have yielded negative 

 results, while the feeding of rabbits with ripe coccidia has brought 

 about the disease in animals presumably healthy ; and, so far as 



* Ballance and Shattock: Trans. Path. Soc. Lond.^ vol. xlii., p. 380. 



International Journal of Microscopy and Natural Science. 

 Third Series. Vol. III. o 



