Summary 557 



are not rare, and are characterised by the absence of any protective 

 action on the part of the blood serum. In these cases, the fixatives, [58 1] 

 whose existence is very probable, remain lodged within the phago- 

 cytes, just as are the cytases. Within these digestive cells the 

 fixatives may quite well fulfil their preparatory role, this being 

 followed immediately by the action of the cytase. The same rule 

 may apply also to the cases of absorption in the unprepared animal, 

 where fixatives are not found in the blood serum, but where they are 

 able to act within phagocytes. 



The excretion of fixatives into the plasmas, which constitutes the 

 rule in cases of acquired immunity, presents an analogy with the 

 excretion of pepsin into the blood. This soluble ferment can and 

 does pass habitually from the stomach into the blood and thence 

 into the urine, where it is often met with. As the pepsin, which only 

 acts in an acid medium, cannot be utilised in the alkaline blood 

 plasma, it is evident that its excretion is only the consequence of a 

 too abundant over-production. 



In recent years great attention has been paid to the essential 

 mechanism of the action of fixatives on the formed elements on the 

 one hand, and on the cytases on the other. According to Ehrlich, 

 the fixatives are bodies intermediate between the two. In pos- 

 session of two haptophore molecular groups, they are capable of 

 entering into chemical combination with the micro-organisms or 

 the animal cells on the one hand, and with the cytases on the other. 

 It is for this reason that Ehrlich applies to them the name of 

 " amboceptors " or " intermediary substances." Based on analogous 

 examples in organic chemistry, Ehrlich thinks that the fixatives 

 serve to introduce the cytases into the cells upon which they have 

 to act. Bordet does not share this view and maintains that the 

 action of the fixatives is not a chemical action in the proper sense 

 of the word, but is a kind of mordanting which sensibilises the formed 

 elements to the fermentative action of the cytases. According to him, 

 the fixatives have no affinity for the cytases and in no way serve 

 them as intermediaries, for which reason he gives to them the 

 name of sensibilising substances. The question is still under 

 discussion, but we may hope that it will soon enter into its final 

 phase. 



According to Ehrlich's theory, the fixatives contain no product 

 coming from the micro-organisms or from the animal cells upon 

 which they are fixed. The fixatives are, according to him, side- 



