CONDITIONAL NEOPLASMS AND SUBTHRESHOLD NEOPLASTIC STATES : A STUDY OF THE TAR TUMORS OF XXXX .

@entity1 @entity5 @entity1185 @entity95 @entity189
The "warts" which tar elicits on @entity95 skin ( @entity1185 , carcinomatoids, frill horns) are true @entity5 , benign growths expressive of slight yet irreversible deviations of epidermal cells from the normal. The neoplastic condition gives the cells a superiority over their neighbors when both are submitted to the same encouraging influences, and then they proliferate into @entity5 . Their state entails such disabilities, though, that they are unable to maintain themselves under ordinary circumstances, and consequently growths composed of them disappear when no longer aided. Often the neoplastic cells resume the normal aspect and habit of life long before the @entity5 mass is gone; and they may persist as part of an apparently normal epidermis, retaining their neoplastic potentialities for months after all signs of the growth have disappeared. In these instances it can be made to appear again, sometimes repeatedly, by non-carcinogenic stimulation of the skin (wound healing, turpentining). There is reason however to suppose that in the end the @entity5 cells, unless helped, die or are cast off. It is plain that the neoplastic state does not necessarily connote independence of behavior or success in @entity5 formation. On the contrary it may render cells unable to survive or endow them with powers which they can exert only under favoring conditions. This is the case with the cells composing the tar warts of @entity95 . In the lack of such conditions the cells of these growths do not manifest themselves but remain in a subthreshold neoplastic state, whereas if aided they form @entity5 . The deviations from the normal represented by the @entity5 of @entity95 are slight and limited in character, but further deviations in larger variety may be superimposed upon them, with result in @entity5 , growths possessed of a greater, though not always absolute, independence. @entity5 usually come about in this way, by successive, step-like deviations from the normal, and so also do the @entity5 which derive from virus-induced @entity1185 as well as many @entity1 @entity189 . After cells have become cancerous they frequently undergo further changes, some apparently step-like in character, and all taking the direction of greater malignancy. The hypotheses that @entity5 are due to somatic mutations and to viruses respectively are discussed in the light of these phenomena.
