THE POISON OF EELS' BLOOD (ICHTHYOTOXINE). 243 



Immunisation against Eels' Blood, The poison of eels' blood 

 also shows itself to be a true toxine by the fact that it is 

 possible by means of it to produce immunity in susceptible 

 animals. 



According to KOSSEL, CAMUS and GLEY, and WEHRMANN and 

 TcHiSTOViTCH, 1 rabbits are the best animals to use for the 

 purpose. From 0*05 to 1 c.c. is first introduced, either by 

 subcutaneous or intravenous injection ; the animals usually 

 stand this dose well, and can then readily be immunised to a 

 higher degree. It is very difficult to immunise guinea-pigs since 

 they u'sually succumb ; dogs bear the treatment well, but yield 

 only weak antisera. Goats, on the other hand, appear to be 

 suitable animals. Hens and pigeons yield only traces of anti- 

 toxine, and that, too, only against the blood-solvent action in 

 vitro. Pigeons are very susceptible to the poison, although their 

 erythrocytes are hardly attacked at all by eels' serum. The 

 formation of an ti toxine is very rapid, and even after three or 

 four injections a serum is obtained of about -f$ to ^V ^he 

 neutralising strength i.e., from 10 to 20 c.c. of serum are 

 required to neutralise 1 c.c. of eels' serum. 



TCHISTOVITCH determined the strength of his serum as follows: 

 Five drops of eels' blood (1 : 10 of a 0*7 per cent, solution of 

 sodium chloride) were treated with increasing doses of antitoxine. 

 The reagent for testing both the hsemolytic and the toxic action, 

 consisted of a few c.c. of rabbits' blood diluted to 20 c.c. 

 Parallel tests were made in each case, and some remarkable 

 results were obtained. Thus, while the resistance offered by the 

 rabbits themselves showed a continual increase, the proportion 

 of antitoxine in their serum did not increase in the same manner ; 

 but, on the contrary, became continually less. 



At the same time, the erythrocytes of these animals also 

 showed special characteristics. KOSSEL and CAMUS and GLEY 

 had simultaneously discovered that the erythrocytes of immun- 

 ised animals were in themselves (i.e., thoroughly freed from 

 serum) under certain conditions refractory to the hsemolytic 

 action of eels' blood. TCHISTOVITCH now discovered that the 

 blood-corpuscles as such dissolved very readily when the pro- 

 portion of antitoxine was high ; but that they were more or less 

 refractory when the amount of antitoxine in the serum decreased. 



There is here a certain parallelism in the phenomena, which, 

 assuming the correctness of the facts, appears to point to a 

 disappearance of the receptors for eel toxine, both in the body 



1 Tchistovitch, " Etudes 'sur 1'immunisation centre le s^rum d'anguille," 

 Ann. Past., xiii., 406, 1899. 



