308 PROTEIN POISONS 



product or is due to a modification in. the former we cannot 

 say. For the present we will confine our attention to the 

 general, non-specific proteolytic ferment in normal guinea- 

 pig serum. Like all ferments, it is supposed to consist of 

 two parts. (1) A thermostabile part, known as the ambo- 

 ceptor, and (2) a thermolabile part, known as complement 

 or alexin. The latter is destroyed by a temperature of 56, 

 and serum heated to this point is inactivated. It has been 

 found by most observers that inactivated serum from the 

 guinea-pig, or, in fact, any inactivated ferment solution, 

 does not function. Seitz 1 found in a few instances that 

 by incubating certain bacteria with inactivated serum he 

 obtained a free poison, but this is contradicted by the 

 experience of so many investigators that we must conclude 

 that his technique was defective. 2 There are, however, 

 some points of real interest in connection with this reaction. 

 Since bacteria and certain other proteins, when incubated 

 with normal serum, yield a soluble and active poison, why 

 does this reaction not occur when these proteins in the 

 unbroken condition are injected directly into the blood? 

 The only answer to this question seems to be that the ferment 

 is in a more readily available form in the serum than it is 

 in blood. The ferment in the serum probably comes largely 

 from the breaking down of leukocytes. When an unbroken 

 protein is injected into an animal usually the first effect 

 upon the blood is a leukopenia. Certainly there is for a 

 time a diminution of the leukocytes in the peripheral blood. 

 After a time there is a hyperleukocytosis, and this is generally 

 believed to be for the purpose of breaking up the foreign 

 protein. There is, however, another possible explanation. 

 It may be that in the circulatory blood the disruption is 

 carried beyond the point of setting free the poison. It may 

 itself be disrupted and converted into relatively harmless 

 substances. There is also the possibility that the inclusion 

 of the foreign protein by the phagocyte may delay the 

 disruption of the former. 



1 Zeitsch. f. Immunitatsforschung, 1911, xi, 588. 



2 See article by Lura, ibid., 1912, xii, 467. 



