ON ILEMOLYTIC RECEPTORS 127 



later contains a perceptible amount. We have employed 

 a small Berkefeld filter and a Chamberland, and in both 

 cases the results are of the same nature, though, as one 

 would expect, the receptors are more efficiently retained by 

 the Chamberland filter. The following may be quoted as 

 a characteristic example : 



The corpuscles of 200 c.c. of 5 per cent, of suspension are lysed 

 with water, and the fluid is made up to the original volume and a 

 percentage of 0-85 sodium chloride. 



Filtration is then performed by a Chamberland filter, and portions 

 of the first 30 c.c. and the second 20 c.c. respectively are tested for 

 the presence of receptors. The fluid is arranged in a series of tubes, 

 1 c.c. in each, and five doses of immune-body are added. Comple- 

 ment is then added to the tubes in increasing amounts, and the 

 tubes are allowed to remain in the incubator for two hours. To each 

 tube 1 c.c. of suspension of corpuscles treated with, immune-body 

 is added, and the amount of lysis is observed. At the same time 

 varying amounts of complement alone are tested with treated 

 corpuscles in the usual way. 



It is found that in the case of the first part of the fluid, 1 c.c. treated 

 with immune-body takes up 0-002 c.c. of complement, while in the 

 case of the second portion the amount is 0-01 c.c. As the full amount 

 of complement taken up by all the receptors saturated with immune- 

 body would have been about 0-2 c.c., this means that in the first 

 portion about 1 per" cent, of the receptors passed the filter, and in 

 the second about 5 per cent. We are thus probably safe in concluding 

 that the first few cubic centimetres would be practically free of 

 receptors. 



It occurred to us that the length of time during which 

 the fluid was allowed to stand after the corpuscles were 

 laked, might have some influence on the number of receptors 

 which would pass the filter. We have tested this at varying 

 periods, the corpuscles being laked, for example, during 

 a quarter of an hour, twelve hours, and twenty-four hours, 

 and then filtered. We used the same filter, and found that 

 the amount of receptors which passed through depended on 

 the order in which the three fluids were filtered ; that is, 



