124 PROPERTIES OF ILEMOLYTIC SERA 



The amount of complement taken up is reckoned from 

 the first tube in which complement can be obtained after 

 incubation for two hours at 37 C. 



Example. Centrifugalization of the laked corpuscles is carried on 

 for an hour. To each tuhe seven doses of immune-body are added. 

 The result is 



(a) Upper part of fluid. Amount of complement taken up = 0-09 c.c. 



(b) Lower part of fluid with stromata =0-24 

 M.H.D. of complement ... . = 0-016 

 In another case Centrifugalization was performed for two hours. 



Ten doses of immune-body were added to each tube (in this case 

 only 0-5 c.c. of fluid to be tested was placed in each tube). 

 Upper part of fluid. Amount of complement taken up = 0-007 c.c. 

 Lower part, with sediment = 0-29 



M.H.D. of complement ... . = 0-03 



From such and other experiments we have arrived at 

 the conclusion that it is possible to make a large proportion 

 of the receptors pass to the bottom of the tube, but that 

 it is not possible to free the upper part of the fluid entirely 

 from receptors. 



On examining microscopically the upper part of the fluid 

 obtained by Centrifugalization, we have generally found 

 a few stromata or shadows, though these have seemed in- 

 sufficient to explain the amount of complement taken up ; 

 in one case we could not detect any. (They are distin- 

 guished more easily when some concentrated salt solution 

 is added to the fluid.) We have tested the effect of Cen- 

 trifugalization with a greater strength of salt solution, 

 namely, 1-7 per cent., double the usual strength. In such 

 a fluid the stromata become contracted and are deposited 

 more rapidly. Before the power of taking up complement 

 is estimated, the percentage of salt is reduced to 0-85 by 

 adding an equal volume of sterile water. The following 

 may be taken as an example : 



In (a) Centrifugalization was performed in 0-85 per cent, sodium 

 chloride, in (6) in 1-7 per cent. After Centrifugalization equal amounts 



