A variety of aspects of lymphosarcoma transmission were investigated in adult Triturus viridescens and Rana pipiens. Freshly biopsied and frozen cellular implants of lymphosarcoma from Xenopus laevis were used to induce the cancer in both the newts and the frogs. Cellular implants of these induced tumors were then used allogenically to transmit the cancer. Homogenates of Xenopus tumors and of tumors formed in the newts and frogs were successfully used to pass on the cancer. Filtered homogenate (filter size, 450 mµ) and supernatant fluids of centrifuged homogenate (20,000 × g for 30 min) were also infectious. Both frog and newt tumors could be back-transferred to Xenopus.

Horizontal transmission was demonstrated in newts, and urine collected from lymphosarcoma-bearing frogs was used to transmit the tumor to young adult Xenopus. Newts thymectomized prior to injection with tumor homogenate developed lymphosarcomas, which demonstrates that this lymphoid disease is not thymic dependent.

The implantation of methylcholanthrene crystals with and without the simultaneous injection of tumor homogenate indicated that the carcinogen will not induce the lymphosarcoma in either species tested in the absence of the lymphosarcoma agent. Previous reports of the induction of this tumor should be interpreted in terms of augmentation, rather than induction.


Supported by USPHS Grant CA-08268 from the National Cancer Institute of the NIH and by the Jane Coffin Childs Memorial Fund for Medical Research.

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