328 



Scientific Proceedings (130) 



If we choose the latter temperature as our standard, we may find 

 that extract A becomes saturated on adding to it 400 mgm. of 

 cholsterin per 100 c.c. ; extract B reaches saturation with 500 

 mgm., and extract C is capable of holding in solution as much as 

 600 mgm. of cholesterin per 100 c.c. before reaching the satura- 

 tion point. These three cholesterinized extracts according to our 

 preliminary experiments, approach one another in sensitiveness. 

 Considerably more work will have to be done in this connection. 

 We may find that to replace the lack of non-cholesterin lipoids 

 in a given extract with cholesterin, may lead to difficulties. A 

 number of extracts prepared from different heart muscles are 

 now being tried out and the results with detailed method of 

 standardization of antigen will be reported in a forthcoming 

 paper. It is touched upon here in order to indicate to workers 

 interested in this test, a clue by which one may overcome the 

 variable elements which enter in the alcoholic extraction of dif- 

 ferent lots of beef hearts. 



At present we recommend standardizing the alcoholic extract 

 by means of an approximate color standard as indicated above 

 and cholesterinizing it by adding 400 mgm. per 100 c.c. This 

 amount of cholesterin approaches the saturation point at room 

 temperature of most extracts and is giving good results in our 

 routine work in this laboratory and, to our knowledge, in other 

 laboratories where this test is employed as a regular procedure. 



It is well to cholesterinize amounts of extract which will be 

 likely to last for about a month or two only. Such extracts show 

 a tendency to become slightly less sensitive on prolonged standing. 



If a given extract is incapable of holding in solution 400 mgm. 

 of cholesterin per 100 c.c. at room temperature, the mixture 

 should be kept in the incubator in the dark and the tendency of 

 the crystalization of the cholesterin will thus be avoided. 



Procedure I (Original). 

 Principle : The mechanism of this procedure is believed to be 

 as follows. The antigen consists of a highly concentrated solu- 

 tion of apparently specific lipoids. Approximately the smallest 

 amount of salt solution (0.85 per cent. NaCl) is added to a given 

 amount of antigen which will result in an opalescent mixture. 

 This renders the mixture unstable with reference to precipitation 

 as indicated by the fact that it will, in practically all cases, become 



