102<»] VETERINARY MEDICINE. 781 



nonnul blood. The use of such a bahiiiced solution in place of normal salt 

 solution* is said to result in a marked reduction of the hemolysis produced in 

 the controls. 



(2) Determinations of the proportion of cells heniolyzed in each mixture 

 rather than of the number of cells. This is done by estimating the color of the 

 decantate from each tube after the partially hemolyzed mixture is centrifugal- 

 ized relative to that of the solution obtainetl by hemolyzing the residual cells of 

 the same tube in a volume of distilled water equal to that of the original hemo- 

 lytic mixture. The standard solution used in known dilutions for comparison 

 is made by diluting 1 cc. of a 5 per cent suspension of cells with 24 cc. of dis- 

 tilled water. The comparis<m is best made in a darkened room, using Nessler 

 tubes which are held in front of a diffusely illuminated slit. 



(3) Interpretation of the results of titration by determining the relative 

 amounts of complements necessary to cause given degrees of hemolysis in a 

 dehnite length of time. The end points selected are 80, 60, 40, and 20 per cent 

 hemolysis. By plotting concentrations of complement as abscissas and the cor- 

 responding grades of hemolysis as ordinates, smooth curves are obtained from 

 which the efficiency of different samples of complement may be determined accu- 

 rately if corrections are made for color c<Mitributed to the decantate by the 

 complement itself, for hemolysis occurring in the absence of complement, and 

 for the drop of decantate left with the sediment of the cells. 



" It is hoped that the presentation of this method for the precise titration of 

 complement may serve as an incentive to quantitative studies of complement, for 

 we must admit that the qualitative work of a generation of students has fur- 

 nished but slight foundation for a valid theory by which to account for the 

 complementing power of serum." 



The regeneration of complement after radiation or heating, S. C. Brooks 

 {Jour, ^fcd. Research. J,l (1920), No. J,, pp. Jtll-42Jt, fi(/s. 7).— With the use of 

 the titration method described above, a conrparison was made between the 

 behavior of .samples of complement whicli had been partially inactivated by 

 heat and that of similar samples partially inactivated by ultraviolet light. The 

 complement used was fresh guinea pig serum diluted in a modified Ringer's 

 solution. Normal and treated samples of this complenrent in varying dilutions 

 were tested against sheep's red blood cells sensitized with from 2 to 3 units of 

 amboceptor (rabbit's antisheep serum). The results of this investigation are 

 summarize<l as follows: 



"After partial photoinactivation, complement deteriorates slowly at 7° and 

 more rapidly at 37° C. The rate of deterioration is the same as that of normal 

 conrplement. 



" After partial thermoinactivation, complement recovers a portion of its lost 

 hemolytic power, the recovery taking place more rapidly at 37° than at 7° C. 

 This recovery or regeneration may restore at least one-third of the lost hemolytic 

 power. 



" It is suggested that the regenei-ation may be attributable to the presence of 

 a parent substance which is less sensitive to high temperatures than the ht'mo- 

 lytic principle, but equally sensitive to radiation." 



Researches on agglutination. — Continued action of an electric current 

 on agglutinating sera, P. Zannei^li {Ann. Ig. [Rome], 30 {1920), No. 7, pp. 

 JfOo-.'/Ol). — To study the action of the electric current on agglutinating sera, 

 typhoid, paratyphoid A, paratyphoid B, and cholera agglutinating sera were 

 exposed in U tubes to an electric current of 8 volts aud 0.0005 ampere for a 

 period of two hours. At the end of this time that portion of the serum in the 

 branch of the tube corresponding to the cathode was turbid with a strongly 



