PROPERTIES OF COMPLEMENTOIDS 63 



than guinea-pig's serum heated at 55 C., as the haemolytic 

 dose of complement is less in the former medium. 



It is to be noted at the outset that the corpuscles used 

 are those of the ox, the immune-body is obtained from the 

 rabbit by injecting it with ox's corpuscles, and the comple- 

 ment is that of the guinea-pig. It seemed to us a some- 

 what curious circumstance that the heated serum of the 

 guinea-pig should be a specially suitable medium for suspend- 

 ing the corpuscles of the ox, and have considered it desirable 

 to test the haemolytic dose of complement when the corpuscles 

 are suspended in different media, especially in the heated 

 sera of different animals. Such heated sera, though bereft 

 of complement or rather of the toxic action of complement, 

 contain complementoids according to Ehrlich's view ; this 

 matter will be referred to below. So far as we know no 

 observations of this kind have been made. 



It is scarcely necessary to state that all the experiments 

 were carried out with the different media of suspension 

 at the same time and for the same periods of time. The 

 results may be given in tabular form, and the doses are 

 most conveniently given in terms of the minimum haemolytic 

 dose in salt solution. 



Ox's corpuscles. Immune-body from Rabbit. Guinea- 

 pig's complement. 



E&molytic doses of 

 complement necessary 



Medium of suspension. for complete lysis. 



0'85 per cent, sodium chloride solution ... 1 



Ox's serum 55 2 



Guinea-pig's serum 55 ...... 5-5 



Guinea-pig's serum 55 and -85 per cent. 



salt solution, equal parts ..... 3+ 



Rabbit's serum 55 2+ 



N.B. The relative dosage varies considerably with different samples of 

 serum, but the figures given may be taken as a fair average. 



It appears clearly from this table that the dose of comple- 

 ment necessary for haemolysis varies greatly according to 

 the medium in which the corpuscles are suspended, and 



