CONCERNING H.EMOLYSIXS. 15 



properties for other blood-cells were entirely destroyed, it was still 

 able to typically reactivate the particular immune body here con- 

 cerned. 1 In another series of goats* however, the result was different, 

 for heating the serum to 56 C. destroyed its reactivating properties 

 completely. These sera then contained exclusively a thermolabile 

 addiment which, like the thermostabile addiment, fitted the immune 

 body. We must therefore conclude that the immune body developed 

 by this immunization is capable of being activated by addiments 

 of two kinds, which differ from each other by their resistance 

 to thermic influences and which are both present in normal serum. 



It is probable that both kinds of addiment can be present in 

 goat serum at the same time, but that in most cases only one, the 

 thermolabile, is present. The varying behavior toward thermic in- 

 fluences, manifested by the sera of our immunized animals, would thus 

 be easily explained. We assume that the same immune body was 

 present in both cases, but that the serum of the goat first immunized con- 

 tained only the thermolabile addiment, while the sera of the animals 

 examined later contained also the thermostabile addiment. In this 

 connection, the fact that, previous to the commencement of immu- 

 nization, we were able to demonstrate a considerable content of 

 thermostabile addiment in the serum of the third animal (buck II) 

 is of considerable interest. 



Having thus arrived at some understanding of the action of the 

 hsemolytic sera produced by immunization it seemed essential that 

 we extend our investigations to the hamolytic properties of normal 

 sera. These properties had long been known and had been studied 

 particularly by Buchner and his pupils. 2 



The fact that the hsemolytic action of normal serum is destroyed 

 by moderate heat led us to believe that the normal hsemolysins are 



1 As it is thus possible to destroy all the normal lysins (which interfere with 

 the experiment) it ought to be possible to determine whether a similar heat- 

 resisting addiment also occurs in the serum of other species. We succeeded 

 in demonstrating its presence in varying amounts in the serum of a sheep and 

 of a calf, but failed to find it in serum of a dog or rabbit. 



2 It is very probable that certain forms of hapmoglobinuria originate through 

 analogous haemolysins. Many years ago Ehrlich showed that the hremoglobi- 

 nuria ex frigore was caused, not by any particular sensitiveness of the erythro- 

 cytes to cold, but by certain poisons produced, especially by the vessels, as a 

 result of the cold. Possibly also such autolysins play an important role in. 

 the convalescence of severe anaemias. 



