ON ELEMOLYTIC RECEPTORS 123 



These examples show clearly that the receptors vary in 

 their resistance to heat. While on the one hand it appears 

 that a small proportion of the receptors are destroyed by 

 exposure for ten minutes at 65 C., on the other hand a fairly 

 large proportion show a high degree of resistance, about 

 a quarter of the original number withstanding a temperature 

 of 100 C. for over an hour. This latter proportion is 

 probably rather under the real amount, as when the higher 

 temperatures are used brownish flocculi are formed, and 

 therefore both immune-body and complement will have 

 difficulty in penetrating to the centre of these and thus 

 saturating the receptors. 



ON THE RELATIONS OF THE RECEPTORS TO STROMATA 

 1. Experiments by Centrifugalization. 



Having now a satisfactory test for the presence of re- 

 ceptors, we can determine, after the corpuscles have been 

 lysed, whether on Centrifugalization the receptors are to be 

 found in the deposit or are left in the supernatant fluid. 

 We have carried out such experiments both when the cor- 

 puscles are laked with water and when lysis is produced by 

 a minimum dose of haemolytic serum. 



(a) Laking with water. The corpuscles are laked accord- 

 ing to the description given above, sodium chloride being 

 afterwards added so as to make up to the original con- 

 centration of 0-85 per cent. The red fluid is then centri- 

 fugalized for varying periods, the centrifuge running about 

 3000 revolutions per minute. The fluid in the tubes is then 

 divided into two equal parts, the upper clear fluid, and 

 the lower portion containing the deposit. The latter is 

 then thoroughly shaken so as to distribute the stromata 

 equally, and the two fluids are distributed in two series of 

 tubes, each containing 1 c.c. A number (seven to ten) of 

 doses of immune-body are added to each tube, and then 

 to the tubes in series increasing amounts of complement. 



