BACTERIOLYSINS AND H^MOLYSINS 



89 



This property is well illustrated by the following 

 protocol from Park. 



It is at once apparent that the number of bacteria 

 introduced is an important factor, the normal serum 

 being able to kill off only a certain number. 



Active and Inactive Normal Serum. In taking 

 up the study of the haemolytic action of normal 

 serum Ehrlich and Morgenroth sought par- 

 ticularly to discover whether in normal serum 

 the haemolytic property depended on the action of 

 a single substance, the complement (Buchner's 

 alexin), or whether here as in the specific haemo- 

 lytic serum it depended on the combined action 

 of two substances. For this purpose they used 

 guinea-pig blood, which is dissolved by normal 

 dog serum. If this serum was heated to 55 C., it 

 lost its haemolytic power. It was necessary now 

 to show that in this inactive dog serum there 

 remained a second substance which could be reacti- 

 vated after the manner of reactivating an old 

 specific haemolytic serum. This had its difficulties, 

 for they could not add normal dog serum. This, 

 as we saw, is already haemolytic for guinea-pig 



