Resorption of albuminoid fluids 113 



guinea-pig the macrocytase of the rabbit's serum dissolves them very 

 readily. Hence the conclusion that in the haemotoxic serum of the 

 guinea-pig there must be present a quantity of fixative sufficient to 

 allow of the solution of the red corpuscles by the macrocytase of the 

 rabbit's serum. This antitoxic serum, therefore, which only prevents 

 the haemolysis on the condition of being added in comparatively 

 large quantity, contains very little antifixative. When, by heating 

 this serum to 55 C. we destroy the rabbit's macrocytase, the mixture 

 of antitoxic serum of the rabbit and haemotoxic serum of the guinea- 

 pig, which ordinarily dissolves the red corpuscles of the rabbit, now 

 leaves them intact. The reason is that the free fixative contained 

 in this mixture does not find any available macrocytase : that of the 

 rabbit being destroyed by the heating, and that of the guinea-pig 

 neutralised by the antitoxic serum. The experiment I have just 

 described proves that this antitoxic serum contains specific anticytase. 

 This anticytase is capable of neutralising the guinea-pig's macrocytase, 

 but is altogether powerless against that of the rabbit. This last cir- 

 cumstance allows us to investigate whether the antitoxic serum of 

 the rabbit contains, in addition to anticytase, a specific antifixative. 

 Bordet prepared a mixture of antitoxic serum of the rabbit, heated 

 to 55 C., with haemotoxic serum of the guinea-pig, also heated to 

 55 C. In this mixture the two macrocytases (that of rabbit and that 

 of guinea-pig) have been destroyed by heat, but the antitoxins of the 

 rabbit's serum and the fixative of the haemotoxic serum have re- 

 mained intact. This mixture owing to its want of macrocytases was [121] 

 incapable of dissolving the red corpuscles of the rabbit. By adding 

 to it some fresh unheated serum from a normal rabbit the rabbit's 

 macrocytase was introduced. As the latter could not be neutralised 

 by the anticytase of the antitoxic serum and was incapable, by itself, 

 of dissolving the red corpuscles of the rabbit, it was unable to produce 

 haemolysis except on the condition that there is in the mixture a 

 sufficient quantity of unneutralised free specific fixative. As a 

 matter of fact, the red corpuscles of the rabbit are not dissolved in 

 the mixture described; this proves that the fixative had become 

 inactive in consequence of the presence of an antifixative in the 

 antitoxic serum of the rabbit. I need not enter into further details 

 of Bordet's experiments, which have fully demonstrated the fact that 

 in the antitoxic serum of his rabbits there were really two antitoxins ; 

 an anticytase abundant in quantity, and an antifixative present in 

 much smaller amount 



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