Neoplasms in C3H mice which received AK-leukemic extracts when newborn.

A series of papers by Gross (6, 7, 10) has de scribed the induction of leukemia, parotid gland tumors, and sarcomas in aging C3H, C57BR/cd, and C57BL mice which received cell-free leukemic extracts or filtrates when newborn. The inocula tion materials were obtained chiefly from AK-n1 and C58 mice which are characterized by a very high (80-90 per cent) incidence of spontaneous leukemia. In contrast, the recipient mice repre sented strains exhibiting a low incidence (4 per cent or less) of spontaneous leukemia. Law (12,13), Stewart (15,16), and Woolley (18) have also investigated this problem, with some what divergent results. Law, as well as Stewart, failed to demonstrate an incidence of leukemia in experimental mice significantly higher than that occurring in control mice. Both workers did, how ever, obtain parotid gland tumors in inoculated but not in control mice. Woolley's data offer con firmation of Gross's findings. As will be empha