Union of Alexin with Specific Precipitates. 147 



coagulum with fibrinogen in a few minutes. As thrombin is made 

 with 8 per cent. NaCl solution, it was diluted to approximate 

 isotonicity, m/6. In order to still further control any possible 

 osmotic effects from hypotonicity, solutions of m/5 and m/4 con- 

 centrations were also used to dilute the serum. 



The system consisted of 1 c.c. of 1-100 immune serum, plus 

 0.1 c.c. washed ox corpuscles (5 per cent, emulsion), plus thrombin 

 in amounts varying from 0.05 c.c. to 0.3 c.c. As a control one 

 tube was always prepared with normal serum (alexin) instead of 

 thrombin. The tubes were kept at a temperature of 36-37 0 C. 



The results can be stated in a few words. The control tubes 

 showed complete hemolysis in from fifteen to thirty minutes. In 

 no instance was there a trace of hemolysis even after several 

 hours, in the tubes containing thrombin. The corpuscles settled 

 out of the solution and left a clear supernatant fluid, not even 

 tinged with hemoglobin. Having obtained this negative result 

 with thrombin, I then tried solutions of fibrinogen and of serum- 

 globulin, in order to make the matter complete. Exactly the 

 same results were obtained, and I think we may conclude that 

 whatever alexin may be, it is certainly not identical with thrombin 

 or the globulins. 



95 (79i) 



On the nature of the union of alexin with specific precipitates. 

 By Hans Zinsser, M.D. 



[Division of Bacteriology, Medical Department, Stanford University.] 



In continuing studies on the nature of alexin fixation by 

 mixtures of unformed proteins and their antisera, it occurred to 

 the writer to examine whether the alexin fixation which is exerted 

 by specific precipitates was subject to the same conditions that 

 prevail in the case of sensitized cell complexes in their relations 

 to the alexin fractions as first obtained by Ferrata. It is well- 

 known, of course, that by dialysis, by dilution with weak acid in 

 distilled water and by a number of other methods of globulin 

 precipitation, the alexin or complement can be divided into two 

 functional parts, one which comes down with the globulins, the 



