354 H. B. ANDERVONT 



parotid tumors in 11 % of C3H mice and cell-free extracts of these 

 induced parotid tumors induced similar tumors in 7 % of other C3H 

 animals. 



Other investigators observed the appearance of parotid tumors in their 

 animals while trying to confirm Gross' observations on the detection of the 

 leukemia virus. Stewart (1955a) found them, independently, in strain 

 C3H mice which had received filtrates or extracts of spontaneous or trans- 

 planted AKR or AK/n leukemias. It is of interest that Stewart prepared 

 extracts from organs of normal C3H mice and that these extracts failed to 

 produce parotid tumors when injected into other C3H mice. Stewart (1955b) 

 also observed parotid tumors in (C3H X AKR)Fj hybrids that had received 

 filtrates of tissues from a transplanted AK/n leukemia or from leukemias 

 arising in other (C3H X AKR)F X hybrids. 



Stewart et al. (1957a) exposed tissue cultures of monkey kidney to extracts 

 of parotid tumors and, after a few passages, injected the tissue culture 

 supernatant fluids into (C3H X AKR)F X hybrids; of 66 treated hybrids, 34 

 developed parotid tumors. Cell-free extracts from a transplanted AK/n 

 leukemia and a paraganglioma also induced parotid tumor in similar hybrids. 

 They also administered cell-free extracts from various sources to strain C3H 

 mice and (C3H x AKR)Fj hybrids and, in contrast to the findings of Gross, 

 none of the extracts elicited parotid tumors. Tissue sources for some of these 

 extracts were: parotid tumors, mammary tumors from C3H mice, normal C3H 

 tissues, and normal AKR tissues. Thus, these investigators found parotid 

 tumors in only those mice which had received material from tissue culture 

 preparations, from a transplanted AK/n leukemia, or from a paraganglioma. 

 Stewart et al. (1957b), during a study designed to ascertain whether the virus 

 of lymphocytic choriomeningitis could be implicated in the production of 

 leukemia, added cell-free extracts of a transplanted AK/n leukemia to tissue 

 cultures of monkey kidney and to cultures of chick chorioallantoic membrane. 

 When fluids from these cultures were injected into (C3H X AKR)F X hybrids, 

 some of the test animals developed parotid tumors. 



Law et al. (1955) noted the occurrence of parotid tumors in strain C3H mice, 

 (C3H x AKR)F 2 hybrids, and (C3H X C3H/Fg)F 1 hybrids after they had 

 received preparations from leukemic tissues. They made the significant 

 observation that the tumors appeared in certain litters: of 55 C3H, 17 (C3H x 

 AKR)F l5 and 10 (C3H x C3H/Fg)F 1 litters, the tumors were confined to 8, 

 5, and 3 litters, respectively. It is of interest that 10 of 28 (C3H X C3H/Fg)F 1 

 treated hybrids developed parotid tumors and, while none was observed in 

 untreated C3H or AKR mice, 2 spontaneous cases occurred in untreated 

 C3H/Fg mice. When filtrates from parotid tumors were admin istered to C3H 

 mice or (C3H X AKR)F X hybrids, few parotid tumors occurred in the test 

 mice, but a footnote contained information that transplants of an induced 



