358 H. B. ANDERVONT 



tumors in another (C3H X C3H/Fg)F 1 mouse were of interest because they 

 displayed the histological morphology of parotid gland tumors. 



4. Adrenal Tumors 



These tumors, of medullary origin, were found by Stewart (1955a) in C3H 

 mice inoculated with extracts of filtrates from a transplanted leukemia 

 originating in a C3H mouse that had received, into the anterior chamber of 

 the eye, a fetal thymic transplant which had been exposed to an extract of an 

 AKR transplanted leukemia. Of 25 inoculated mice, 9 developed adrenal 

 tumors, of which 7 were bilateral. The variety of other tumors in mice with 

 adrenal tumors was of interest: 3 had adrenal tumors only; 2 had parotid 

 tumors; 1 had a subcutaneous sarcoma; 1 had an ovarian tumor of the same 

 cell morphology as the adrenal tumor; 1 had a similar ovarian tumor, a 

 parotid tumor, and a mammary tumor; 1 had a parotid tumor, a mammary 

 tumor, and a Harderian-gland tumor. Some of the adrenal tumors metasta- 

 sized and subcutaneous transplants killed their hosts in from 8 to 12 weeks. 

 Five other adrenal tumors were included in a later report by Stewart (1955b). 

 These all rose in (C3H x AKR)F X hybrid mice, of which 4 had received 

 filtrates from a transplanted AK/n leukemia and, of these 4 animals, 3 had 

 mammary tumors and parotid tumors and 1 an adrenal tumor only. Stewart 

 et al. (1957a) reported the occurrence of adrenal tumors in 6 (C3H X AKR)F X 

 hybrids after they had received supernatant fluids from tissue cultures. These 

 mice had also developed parotid tumors. The multiplicity of other tumors in 

 mice with adrenal tumors could be significant. 



Law et al. (1955) confirmed the occurrence of adrenal tumors in C3H mice 

 that had received leukemic materials. Two mice developed tumors after 

 receiving materials from AKR leukemic tissues, and both had parotid tumors. 

 One tumor was transplanted and the workers found it to be a good source of 

 materials for the production of parotid tumors. Stewart et al. (1957a) used 

 cell-free extracts of adrenal tumors to inoculate 35 strains C3H and 26 

 (C3H X AKR)F X hybrids of which only one C3H mouse develoj)ed a tumor 

 and this was an adrenal tumor. Gross (1957b) also observed the occurrence of 

 adrenal tumors in his experimental animals. 



5. Discussion 



These studies of mouse leukemia permit few definite conclusions. This 

 state of affairs is to be expected, not only because of the short period of 

 elapsed time since the first observations were published, but because the 

 problem has become involved in a complex of different tumor types. Gross 

 (1957b) has assembled impressive evidence that cell-free extracts of leukemic 

 tissues from AK/n mice contain an agent which promotes the occurrence of 



