256 VENOMS 



of a very neat and simple method, and with a sufficient degree of 

 accuracy for practical purposes, the antitoxic power of an anti- 

 venomous serum by measuring its antih(Bmolytic power. ^ 



To this end it is sufficient to cause variable doses of serum to 

 act on a given quantity of defibrinated horse- or rat-blood, to which 

 a constant dose of venom is then added. We employ, for example, 

 a 5 per cent, dilution of defibrinated horse-blood, which is portioned 

 out in doses of 1 c.c. into a series of test-tubes. To each of these 

 tubes in succession is added a progressively increasing quantity of 

 the serum for titration, starting with O'Ol c.c, and continuing with 

 O'O^ c.c, 0"0;3 c.c, kc, up to 0"1 cc A control tube receives no serum. 

 There are then introduced into all the tubes 1 decimilligramme of 

 venom and 0"2 c.c. of normal horse-serum, deprived of alexin by 

 previous heating for half an hour at 58 C. At a temperature of 

 about IG' C. haemolysis commences to manifest itself in the control 

 tube in from fifteen to twenty minutes. It takes place in the other 

 tubes with a retardation which varies with the dose of serum 

 added. Tubes are to be noticed in which it does not occur even 

 after the lapse of a couple of hours. 



Experience shovv's that we may consider as good for therapeutic 

 use serums which, in a dose of 0'05 c.c, completely prevent haemo- 

 lysis by 1 decimilligramme of Colubeine venom, such as that of 

 Cobra, Krait, &c., and those that in a dose of 0"7 c.c, prevent 

 haemolysis by 1 milligramme of the venom of LacJicsis or Vipera 

 hems. 



By a method calculated upon the foregoing, it is likewise 

 possible to measure the antihinnorrhagic activity of an anti- 

 venomous serum, for the parallelism existing between the antl- 

 nenrotoxic and antihaiiwhjtic actions of serums occurs again, as 

 I have been able to establish in conjunction with Noc, between 

 the antihamorrhagic and antiprotcolytic action of the same serums. 



' Calmette, Comptcfi reiidits dc I'Acadrniic den Sciences, 1902, No. 24 ; Preston 

 Kyes, Berlhier kliniscJic Wochenschrift, 1904, No. 19. 



