388 COLLECTED STUDIES IN IMMUNITY. 



That they appear to play this role is due to the action of what I have 

 termed the "horror autotoxicus," which prevents the production 

 within the organism of amboceptors directed against its own tissues. 



In this "horror autotoxicus " we are dealing with a well-adapted 

 regulatory contrivance which it may be well to discuss briefly. The 

 investigations of numerous authors have shown that by injecting 

 animals with any kind of foreign cell material cytotoxic substances 

 can be produced directed exactly against the material used for im- 

 munization. Thus if a dog is immunized with an emulsion of goose 

 brain, it will be found that the dog's serum will be highly toxic only 

 for geese, killing these animals with cerebral symptoms. In the same 

 way we can produce other poisons, hepatotoxins, nephrotoxins, etc., 

 each of which acts only on a certain organ of a particular species. 

 In human pathology, however, we must consider the absorption of 

 the body's own constituents and not of those of other bodies. The 

 former may occur under many conditions; for example, in hemorrhages 

 into the body cavities, in the absorption of lymph-gland tumors, in 

 the febrile waste of body parenchyma. It would be dysteleological 

 to the highest degree if under these circumstances poisons against 

 the body's own parenchyma, auto toxins, were to arise. I have 

 attempted to solve this question by injecting goats with the blood of 

 other goats. The sera of animals so treated did not dissolve their 

 own blood-cells, but dissolved those of other goats. Hence it did 

 not contain an autotoxin, but an "isotoxin," in conformity with the 

 law to which I give the name "horror autotoxicus." 



I believe that the isotoxins may perhaps come to play an im- 

 portant role in diagnosis and pathology. In the serum of dogs in 

 which he had produced a chromium nephritis, Metchnikoff found 

 that an isonephro toxin had developed, for when this serum was 

 injected into normal dogs it produced a nephritis. It is more than 

 probable that in man also the greatest variety of isotoxins is formed. 

 In the case of the blood this has already been positively demonstrated 

 by a number of authors, such as Landsteiner, Ascoli, etc. 



With the exception of the red blood corpuscles we cannot, of 

 course, undertake any studies in man concerning the isotoxins of 

 the parenchyma. Many considerations, however, indicate that it 

 will be possible to carry out these experiments on monkeys and so 

 gain a new foundation for pathology and therapy in man. 



The number of combinations present in the blood serum and 

 making up the ever-changing haptin apparatus is infinitely great. 



