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 investigators. 
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 globulins 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 recently 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 1 part of venom solution, varying in 
strength from o.1 per cent to 0.0001 per cent, and observed the amount of pre- 
cipitate formed after 18 to 24 hours. 1 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 
snake poisons. Lancet, 1902, II, 431. 
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