CHAPTER XXVI. 



PRECIPITIN-REACTION WITH SNAKE VENOM. 



That a comparatively specific precipitating substance is developed in the 

 serum of animals through repeated injections of the serums of alien species 

 or various other proteid substances was first shown by Bordet and then 

 carefully worked out in detail by Nuttall, Uhlenhuth, Wassermann .and 

 Schiitze, Myers, Linossier and Lemoine, and others. The precipitation reac- 

 tion has been shown to be highly specific, but not absolutely so. Besides 

 the specific precipitins for numerous kinds of serums of different species, 

 including human serum, precipitins for such proteids as casein of milk, the 

 albumins occurring pathologically in the urine, crystallized egg albumin, 

 pure serum globulin from sheep and from bullock, Witte's peptone, [and 

 muscle have also been produced by various im^estigators. 



Nuttall observed that the reaction is more intense when the host animal 

 and the animal furnishing the serum for injection are widely distant. Myers 

 found that precipitin prepared with egg albumin does not precipitate other 

 proteids, such as the serum globuhns obtained from the sheep or bullock, and 

 Witte's peptone. Uhlenhuth and Wassermann and Schiitze have worked 

 out the specific nature of the precipitin for human blood and applied this 

 reaction to identify the source of a given unknown blood for the medico- 

 legal purpose. Quite r^ently this reaction has been recommended by 

 Wassermann to detect the adulteration of sausages with certain meats legally 

 prohibited from sale as human diet. According to Noguchi precipitins can 

 be produced even in certain invertebrate animals, such as Crustacea. 



In 1902 Lamb^ first studied the precipitin formation with snake venom 

 and employed this reaction to distinguish between the proteids of different 

 snake venoms. He prepared an immune serum in rabbit with pure cobra 

 venom and obtained a markedly precipitating serum when mixed with the 

 homologous venom (cobra). He tested its precipitating property, 3 or 2 

 parts of the serum being mixed with i part of venom solution, varying in 

 strength from o.i per cent to 0.000 1 per cent, and observed the amount of pre- 

 cipitate formed after 18 to 24 hours, i per cent venom solution was not 

 suitable for the test, as this concentration produced more or less precipitate 

 even with normal rabbit serum. 



Among the results obtained by Lamb special interest is attached to the 

 facts that daboia venom behaved in almost every respect the same as cobra 

 venom: precipitate was formed practically in the same quantity. Secondly, 

 the heated venom solutions (75° C.) of these two venoms — heat-coagulated 

 proteids being removed by filtration — gave just as much precipitate as the 



1 Lamb. On the precipitin of cobra venom : a mean of distinguishing between the proteids of different 

 snake poisons. Lancet, 1902, II, 431. 



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