428 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



which takes place when antigen and immune substances interact, can be 

 made still more specific if the test is carried out at a temperature near the 

 freezing point. But, while Witebsky assumes that the immune serum obtained 

 against the carcinoma of a certain organ as a rule reacts specifically with the 

 antigens prepared from a carcinoma of the same organ, and only exceptionally 

 with cancers from other organs, Lehmann-Facius maintains that the antisera 

 show a positive complement fixation reaction with all kinds of human cancers, 

 and even with cancers of other species. 



But, in addition, Witebsky and Morelli found that if in rabbits immune 

 substances are produced against human sarcoma, these immune substances 

 react with alcohol extracts not only of human sarcoma, but also of carcinoma 

 and even of various normal human organs ; but these substances are species- 

 specific and do not react with rat or chicken sarcoma. However, it is possible 

 to absorb from such immune serum the quota reacting with normal organs 

 and to leave behind the anti-tumor fraction ; also the anti-carcinoma fraction 

 can be specifically absorbed with carcinoma extract, so that in the end only 

 the sarcoma antibody is left in the immune serum. It seems, then, from these 

 and other experiments, that antibodies can be produced against constituents 

 which are specific for cancers in general, but that antigenic differences exist 

 between the various kinds of tumors. These antibodies, and therefore also 

 the antigens producing them, may or may not carry species differentials. 

 However, somewhat different are the more recent results of Lehmann-Facius 

 (1932), who finds that ether extracts of mouse intestines may induce the 

 formation of antisera, which react with cancer extracts of a lipoid nature; 

 lipoid antigens which are present in cancer do not need, therefore, to be 

 specific for the latter, but may occur also in normal organs. 



It is possible to obtain anti-cancer sera under conditions in which species- 

 specific immune bodies do not develop, as for instance, when boiled antigens 

 are injected ; but such methods do not exclude the production of organ-specific 

 immune sera. Some of these observations suggest that the antibodies which 

 are common to various anti-carcinoma sera are organ-specific constituents, and 

 that, correspondingly, the change in the constitution of normal cells, which 

 leads to their transformation into cancer cells, represents a change in the 

 organ rather than in the organismal differentials, which latter seem to be 

 essentially the same in cancer and in normal cells. Accordingly, Witebsky's 

 method of injecting cancer globulins for preparing immune sera against can- 

 cer, can be readily used also for the preparation of organ-specific immune 

 sera if, instead of cancer globulins, globulins from various organs are taken 

 as antigens. 



But, there are still further differences between antigens obtained from cancer 

 and from normal tissues. According to Witebsky, in carcinoma cells the lipoids 

 may exist in a state which makes them readily available as antigens, while 

 in normal organs they are less available, perhaps because they are bound to 

 other cell constituents. 



There are some additional indications of the presence of specific cancer 

 antigens. Hirszfeld and Halber, assuming that there are immune substances 



