ON ILEMOLYTIC RECEPTORS 125 



of fluid were used in the two cases ; in (a) dilution was made with 

 0-85 per cent, sodium chloride, in (b) with water. M.H.D. of comple- 

 ment = 0-015 c.c. 



(a) 1 c.c. of upper part of fluid saturated 



with immune-body took up . . 0-06 c.c. of complement. 



(b) 1 c.c. of upper part of fluid saturated 



with immune-body took up . . 0-035 c.c. of complement. 

 On adding some concentrated salt solution to the fluid in (a), some 

 stromata were seen on microscopic examination, but none could be 

 seen in the fluid (6). 



Such an experiment therefore shows that the freer the 

 fluid is from stromata the fewer are the receptors. But 

 we have never been able by centrifugalization to obtain a fluid 

 in which no receptors could be demonstrated, even although no 

 stromata could be seen in it on microscopic examination. 



(b) Lysis with immune-serum. In this case we add 

 several haemolytic doses of immune-body, allow time for 

 combination, and then produce lysis with the minimum dose 

 of complement. As has been shown above (p. 16), when 

 this procedure is carried out, the receptors remain in union 

 with immune-body, and thus lead to the taking up of 

 additional complement. We can thus test whether such 

 receptors are deposited in the process of centrifugalization. 



Example. To 10 c.c. of suspension of red corpuscles are added 

 eight times the haemolytic dose of immune -body. Time is allowed 

 for combination, and then complete lysis is produced by the minimum 

 dose of complement. The fluid is then centrifugalized for two hours, 

 and it is then distributed as ' upper ' and ' lower ' portions in tubes, 

 0-5 c.c. being placed in each. The power of taking up complement 

 is then tested as before, with the result : 



(a) Upper portion of fluid. Amount of complement 



taken up = 0-05 c.c. 



(b) Lower portion of fluid with deposit. Amount of 



complement taken up = 0-19 



Other experiments have given similar results, the general 

 conclusion being the same as that in the case of corpuscles 

 laked with water. 



