360 Chapter XII 



matter by the oxygen of the air, the surface of the fluid is covered 

 [378] with a layer of liquid paraffin. If the leucocytes are living, the 

 lower blue layer becomes decolorised in a short time (in about two 

 hours) ; when the corpuscles are dead, decoloration does not take 

 place. By adding to the mixture of leucocytes and colouring matter 

 some leucocidin, alone or along with antileucocidic serum, it is possible 

 not only to observe with the naked eye the phenomena which take 

 place in these cases, but also to estimate to some extent the pro- 

 portions of poison and counterpoison. 



All these researches make it clear that the antitoxin acts directly 

 on the leucocidin. Similar facts have been noted as regards cer- 

 tain other organic poisons and their antitoxins. Shortly after the 

 discovery of antileucocidin by Denys and van de Velde, Kanthack 

 made a communication to the Physiological Society in 1896 1 , ex- 

 hibiting tubes in which the coagulating action of Cobra venom on 

 the blood had been prevented by the addition of anti venomous 

 serum. Of all the experiments, however, made to prove the direct 

 action of antitoxin on toxin, Ehrlich's 2 have played the most important 

 part in the study of this question. Ehrlich directed his attention to 

 ricin which, as Robert demonstrated, has the property of agglutinat- 

 ing the red corpuscles of defibrinated blood. This phenomenon can 

 be easily observed in vitro. In tubes containing red blood corpuscles, 

 the addition of ricin causes these corpuscles to agglutinate into 

 clumps and to fall to the bottom of the tube, leaving a clear superna- 

 tant fluid. After adding progressively increasing quantities of antiricic 

 serum to the tubes containing fluid blood and ricin, Ehrlich was able 

 to demonstrate that small quantities of antiricin merely retarded the 

 precipitation of the red corpuscles, whilst larger doses completely pre- 

 vented it. Having studied the proportions of ricin and its antidote, 

 necessary to retard and prevent the fatal poisoning of animals, Ehrlich 

 was struck by the parallelism which is exhibited between the action 

 of the antitoxin in the living animal and that in the test tubes. 



The study of anticytotoxins, discussed in the fifth chapter, has 

 furnished another opportunity of observing the action of antitoxins 

 [379] in vitro. Camus and Gley and H. Kossel were the first to observe 

 the action in vitro of antitoxic serum against the ichthyotoxin of 

 eel's serum. Since this observation, this phenomenon has been 

 repeatedly studied in the antihaemolysins and antispermotoxins. 



1 [At a meeting held at St Bartholomew's Hospital, London, cited by Stephens 

 and Myers in Journ. Path, and Bacterial, Edin. and London, 1898, vol. v, p. 280.] 



2 Fortschr. d. Med., Berlin, 1897, Jahrg. xv, S. 41. 



