INTRODUCTORY Xvii 
complexity snake venom takes the highest rank among the serum cytolysins. 
Through the exhaustive investigation of various biologists and pathologists 
we know how intricate the amboceptors and complements of various normal 
and immune serums are. Apparently, accepting the interpretation of Ehr- 
lich, these molecules possess similar toxophore atom complex but different 
cytophilic groups. It is only by respecting this delicate specificity that we 
can accomplish the preparation of antivenins and employ them effectively. 
It may be superfluous to mention that the differentiation of these closely 
allied toxic principles was made possible through the immunization reactions 
only. 
On the more theoretical side, snake venom has again been largely instru- 
mental in defining the chemical nature of the interaction of the antigen and 
antibody. C. J. Martin and Cherry, later also Calmette (the former oppo- 
nent to the chemical theory), and many others have contributed much to the 
establishment of the chemical nature of the action. Madsen and Noguchi 
found the reaction between snake venom and antivenin to be reversible and 
follow the law which Arrhenius and Madsen applied to other toxins and 
antitoxins. 
The regeneration of the hemolytic principle from the neutral mixture 
of venom and antivenin has been accomplished by Morgenroth by means of 
dilute acid. This discovery received confirmation from the recent work of 
Calmette and Massol. 
Returning to the more familiar immunization phenomena a few words may 
be added as to the precipitin reaction of snake venom. Lamb and Flexner 
and Noguchi have demonstrated that the proteins contained in the venoms of 
different species of snake are not quite identical so far as the precipitin reac- 
tions with specific immune serums are concerned. Like other immune reac- 
tions this was found to be only relative. 
As to the practical application of the facts gained by innumerable struggles 
and enormous labor, it must be admitted that the crop is not yet fully gar- 
nered, yet the study of venom has brought and is constantly bringing to science 
and humanity great benefits, of a direct and indirect character. 
