112 Chapter V 



fowl, the presence of two substances which act by combining could 

 not he demonstrated. On the other hand, in the serums that were 

 obtained as a result of the treatment of animals by the injection of 

 blood from a different species, it was easy to demonstrate, as we have 

 shown in the preceding chapter, the presence of two constituent 

 substances which are: the macrocytase (alexine, complement) and 

 the fixative (amboceptor of Ehrlich, sensibilising substance of Bordet). 

 For this reason the study of the antihaemotoxins obtained against 

 artificial haemotoxins is endowed with special interest. As the solu- 

 tion of the red corpuscles, in this case, can be prevented either by an 

 antitoxic action directed against the cytase, or by a neutralisation of 

 the fixative (for the concurrence of these two substances is indis- 

 pensable in order that the solution may take place), Bordet asked 

 whether the antitoxic serum, obtained by him in rabbits, is anticy tatic 

 or antifixative, or whether it contains both properties. Before re- 

 solving this problem it was necessary to establish some of the 

 essential characters of artificial antihaemotoxic serums. The principal 

 one amongst them is the resistance of these antihaemotoxins to a 

 temperature of 55 — 60° C. ; even when heated to 70° C. the antihaemo- 

 toxins retain, at least in part, their fundamental property. In this 

 respect these substances differ from the cytases and approach the 

 precipitins, fixatives and agglutinins. 



The very exact experiments carried out by Bordet have demon- 

 strated that in the serum of rabbits, treated with the specific 

 [120] haemotoxic serum of guinea-pigs, two substances, an anticytase and 

 an antifixative, are found in combination. The former of these 

 antitoxins is found in abundance, but the amount of antifixative is 

 veiy small. Bordet was led to this result in the following way. To 

 prevent the solution of the red corpuscles of the rabbit in the haemo- 

 toxic serum of the guinea-pig, it was necessary for him to add a 

 considerable dose (10 to 20 times) of the antitoxic serum. When, 

 however, he heated the latter to 55° C. the quantity of this serum 

 necessary to prevent haemolysis could be reduced very considerably. 

 In place of its being necessary to add to the haemotoxic serum 10 or 

 20 volumes of antitoxic serum, it was sufficient to add three or 

 sometimes only two volumes of this heated serum. As we know 

 already, heating to 55° C. destroys the macrocytase which should be 

 found in the antitoxic blood of the rabbit. This cytase by itself is 

 incapable of dissolving the red corpuscles of the same species ; but 

 when it is added to the fixative of the haemotoxic serum of the 



