110 Chapter V 



substance which is precipitated by alcohol and certain salts. Like the 

 precipitins and the diastase which digests gelatine, antirennet resists 

 a temperature of 55 56 C. ; even heating to 58 C. has no effect on 

 the antirennet serum. At 60 C., however, the heat begins to exert an 

 injurious effect, and after three hours at 62 C. the serum has lost 

 all power to prevent the coagulation of the casein by antirennet. 

 Morgenroth and Briot both state that the antirenuet neutralises the 

 rennet by a direct action. 



The cell poisons, or cytotoxins, of animal origin which were 

 treated in the preceding chapter, likewise set up the production of 

 special anti-bodies, or anticytotoxins. The consideration of these latter 

 has a very special interest for those who study the question of immunity 

 from a general point of view. The first discovery of these anticyto- 

 toxins was made in connection with the study of the toxic power of the 

 blood serum of eels. Camus and Gley 1 and, independently of them, 

 H. Kossel 2 demonstrated that animals when treated with increasing 

 doses of eel's serum acquire an antitoxic property which protects 

 their corpuscles against the haemolytic action of ichthyotoxin, or the 

 toxic substance of the blood of eels. Th. Tchistovitch 3 has not only 

 confirmed this discovery, but has added to it new and interesting data. 

 When antitoxic serum is mixed in vitro with red blood corpuscles 

 of the species which furnished the serum and there is added to it 

 some haemolytic eel's serum, it will be found that the red corpuscles 

 remain quite unaltered. In the control tubes, however, in which the 

 antitoxic serum is replaced by normal serum of the same species, the 

 red corpuscles are very readily dissolved under the toxic influence of 

 [118] the eel's serum. In animals (rabbits) that are treated with this latter 

 fluid, there is established not only an antitoxic power of the blood, 

 but the red corpuscles acquire a resisting power more or less pro- 

 nounced against the ichthyotoxin of eel's serum. When the red 

 corpuscles are separated from the serum of rabbits (treated with eel's 

 serum) and some ichthyotoxin is added to them, solution very often 

 does not take place at all. According to the experiments of 

 Tchistovitch there is no direct relation between this acquired re- 

 sistance and the antitoxic power of the blood. Sometimes even a 

 kind of antagonism is observed between the two properties ; that is to 

 say, the red corpuscles of a rabbit whose serum is very antitoxic may 



1 Arch, internal, de Pharmacodyn., Bruxelles et Paris, 1898, t. in and iv. 



2 Berl. klin. Wchnschr., 1898, S. 152. 



3 Ann. de I'lnst. Pasteur, Paris, 1899, t. xm, p. 406. 



