404 Mr. G. Dean. Enquiry into the Nature of the [Apr. 23, 



fresh serum produces a greater effect than results from the two substances 

 acting independently ; in other words, is the action similar to, or identical 

 with, the action of a bacteriolytic amboceptor and complement ? At least 

 two methods may be employed in the study of this problem : one, the direct 

 method, of estimating the activity of the bodies when acting separately and 

 in combination ; the other, indirect, by employing something which will throw 

 out of action one of the constituents of a combination, leaving the other 

 unaffected. 



The Direct Method. 



Experiments with Staphylococci. 

 The ordinary technique was employed. In this experiment 1 volume of 

 leucocytes, 1 volume of coccal emulsion and 1 volume of the serum were 

 employed. The result was as follows : — 



Normal serum of rabbit, fresh, 1 volume 



Immune serum of rabbit, heated to 60° C. for 20 mine., 1 volume 

 1 part immune heated and 4 parts fresh normal serum, 1 volume 



Av 



per 



erage cocci 

 leucocyte. 





11-9 



7-1 



33 



The calculated value of the mixture at the highest estimation does not 

 exceed 19, whereas the experimental value is 33. Some other factor must 

 therefore be at work : in this experiment probably a complementing of the 

 immune heated serum by the fresh serum. 



Another experiment of the same type may be recorded in which a slightly 

 different technique was employed. 



Normal rabbit serum, heated, 1 volume, + 



Immune staphylococcus rabbit serum, heated, 1 volume, + 



Normal salt solution, 1 volume, + 



Leucocytes, 1 volume, + 



Cocci, 1 volume. 



Normal rabbit serum, heated, 1 volume, + 

 Fresh normal rabbit serum, 1 volume, + 

 Normal salt solution, 1 volume, + 

 Leucocytes, 1 volume, + 

 Cocci, 1 volume. 



Normal rabbit serum, heated, 1 volume,* + 



Immune staphylococcus rabbit serum, heated, 1 volume, + 



Normal rabbit serum, fresh, 1 volume, + 



Leucocytes, 1 volume, + 



Cocci, 1 volume. 



Average cocci 

 per leucocyte. 



3-0 



6-9 



15 1 



* This was added to control a factor in another experiment. 



