PROTOZOA AND THE CANCER PROBLEM 



213 



able medium for growth in the degenerating masses accompanying 

 cancer, cannot be regarded as the causes of the disease, and as such 

 saprophytic organisms we must include the ameba Leydenia gemmi- 

 para of Schaudinn ('96), which was found by E. von Leyden ('96) 

 in the peritoneal fluids of ascitic dropsy and associated with cancer. 

 This organism is a definite ameboid rhizopod measuring about 25 /x 

 in diameter. It moves rapidly in body temperatures, by forming 

 flat and lamellose pseudopodia. Structurally it differs from most 

 parasitic rhizopods in having a pulsatile vacuole which contracts 

 ordinarily every fifteen minutes. It reproduces by simple binary 

 division and also by bud formation, the buds often being very minute 

 (3 n to 4: n; cf. intestinal amebae). Schaudinn considered it possible 

 that these organisms may have been the cause of the cancers in the 

 two patients in which they were found, and even compared the buds 

 with the small cell inclusions described by Sawtschenko ('95). He 

 was never inclined to push the suggestion in subsequent work, how- 



FiG. 86 



Spirocheta microgyrata (Low.) var. gaylordi, in cancer tissue of mice. (After Calkins.) 



ever, and later (1903) regarded Leydenia gemmi'para as only a phase 

 in the life history of an intestinal rhizopod Chlamydophrys stercorea 

 (see p. 294). The general belief now is that they had nothing to do 

 with the cause of the disease. 



The organisms of epithelioma contagiosum of fowls and of mol- 

 luscum contagiosum of man are not to be included with such sapro- 

 phytic forms, nor with these degeneration products, but are protozoa 

 directly connected with the disease (see p. 312). 



Similar degenerative products have not been found in mouse cancer, 

 and there is less chance here for secondary infection. One organism, 

 however, discovered by Gaylord ('07), Spirocheta microgyrata gay- 

 lordi, occasionally found in the blood of mice, is invariably found in 

 the stroma of mouse cancer, both in primary and transplanted tumors, 

 and is present in enormous numbers in the more malignant strains 



