Proceedings of the First National Cancer Conference / American Cancer Society and the National Cancer Institute of the U.S. Public Health Serivce, Federal Security Agency.
- National Cancer Conference 1949)
- Date:
- 1949
Licence: Public Domain Mark
Credit: Proceedings of the First National Cancer Conference / American Cancer Society and the National Cancer Institute of the U.S. Public Health Serivce, Federal Security Agency. Source: Wellcome Collection.
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![I] Mutations 2 2 MUTATIONS IN TRANSPLANTABLE TUMORS by GrorGE D. SNELL, SC.D. Roscoe B. Jackson Memorial Laboratory, Bar Harbor, Maine It has frequently been said that the origin of cancer must be essentially mutational in nature. At some stage in the life history of an individual, a cell (or a group of adjacent cells) develops the capacity to overcome those restraints on growth that keep the multiplication of normal cells in check. As the cells multiply, further changes may occur that increase their growth potential. The result is a strain of cells with an inherited capacity for con- tinued multiplication or autonomous growth, in other words, a cancer. In discussing these statements, the first need is for a definition of mutation. I shall use mutation in a broad sense, but one that I think would be accepted by most geneticists. A mutation may be defined as any self-perpetuating change in an organism, a cell, or other self-reproducing unit. ‘The change may be a minor or a major one, but it is always pictured as being discontinuous, and it must be perpetuated in succeeding generations. With this definition in mind, let us examine various experi- mental results that bear on mutational processes as related to can- cer. One of the early discoveries in regard to tumors was that they can be transplanted from one animal to another animal of the same species. This was first accomplished before inbred strains of laboratory animals were developed, but it is uniformly successful only within inbred strains. A number of transplantable tumors have now been carried through hundreds of transplant genera- tions. The Jensen rat sarcoma, perhaps the oldest, has been per-](https://iiif.wellcomecollection.org/image/b3217133x_0044.jp2/full/800%2C/0/default.jpg)
