544 



Dr. It. D. Keith. Relationship between [Feb. 15, 



The following are the results : — 



Colour index. 



Guinea-pig serum control 64 



Unheated serum — 



0-001 c.c 440 



0-0005 „ 155 



0-0001 „ 120 



Serum heated at 55° C. for 15 mins. — 



0001 c.c 450 



0-0005 „ 220 



0-0001 „ 115 



It is evident from these numbers that there is practically no difference 

 between the colour indices of the two series ; which permits the conclusion 

 to be drawn that the haemolytic amboceptor is not quantitatively diminished 

 when the serum is heated at 55° C. for 15 minutes. Kepeated experiments 

 gave exactly similar results and it was found to be a matter of indifference 

 whether the serum was heated en masse or in dilution, even in separate small 

 quantities. 



This fact is illustrated by the following experiment, which was performed 

 to illustrate at the same time another point, namely, that there may be a 

 large amount of haemolytic amboceptor present in a diluted serum without 

 the coexistence of the body inducing phagocytosis. 



Experiment. — Four series of tests, A, B, C, D, each consisting of four 

 tubes, were performed. Into successive tubes of each series 0*01, 0-005, 

 0-003, - 002 c.c. of the immune serum was placed. The amounts were 

 equalised by - 85 saline solution. Series A and C were unheated. Series B 

 and D were heated at 55° C. for 15 minutes. To each tube was then added 

 2 c.c. of a 5-per-cent. suspension of washed ox corpuscles, and to each tube 

 of series A and B 0'2 c.c. of fresh guinea-pig serum (i.e., one unheated, and 

 one heated series was complemented). All the tubes were placed at 37° C. 

 for two hours. It was then found that series A and B showed exactly 

 corresponding degrees of haemolysis. 



Cubic 

 centimetres. 



A. 



Unheated and 

 complemented. 



B. 



Heated and 

 complemented. 



o-ooi 



0-005 

 0-003 

 0-002 



Almost complete 



Marked 



Slight 



Slight 



Almost complete 



Marked 



Slight 



Slight 



