ILEMOLYSIS 215 



times with saline it no longer hsemolyses. Red corpuscles 

 act, however, as antigen, and by injecting them into an 

 animal hsemolysin is formed in large amount and is 

 specific, hsemolysing only the corpuscles with which it 

 has been formed. To such an artificially formed hsemo- 

 lysin the name of " immune hsemolysin " may be given. 

 An immune hsemolytic serum may be very active, hsemo- 

 lysing up to dilutions of 1 in 1,000, 1 in 2,000, or more. 



The hsemolytic serum, whether natural or immune, acts 

 only when fresh if it be kept for a week or be heated to 

 56 C. it loses its hsemolytic power. Such an inactive 

 serum may be activated, or rendered hsemolytic once more, 

 by the addition of fresh normal serum. The inactive 

 hsemolytic serum retains its power of being activated by 

 fresh serum for long periods, only slowly deteriorating. 

 It will, therefore, be noticed that bacteriolytic and hsemo- 

 lytic sera are alike in several respects, for both become 

 inactive on keeping or on heating, and both can again 

 be rendered active by the addition of fresh normal serum. 

 The process of hsemolysis, moreover, is similar to that of 

 bacteriolysis, for if corpuscles and fresh normal serum 

 be allowed to interact, be washed, and hsemolytic serum 

 be then added, no hsemolysis takes place ; but if the order 

 of treatment be reversed corpuscles first treated with 

 hsemolytic serum, washed, and the fresh normal serum 

 then added hsemolysis takes place. Specificity is also 

 evinced with hsemolytic serum as with a bacteriolytic 

 one ; an immune hsemolytic serum hsemolyses only the 

 corpuscles with which it was prepared. There is, there- 

 fore, a complete analogy in the activities of hsemolytic 

 and of bacteriolytic sera. The hsemolysin may be 

 regarded as an amboceptor or immune body which is 

 active only in the presence of complement. Moreover, 

 the complement which hsemolyses seems to be identical 

 (and is so for all practical purposes) with the complement 



