Summary 555 



by a high specificity which is never observed in the cytases. The 

 majority of the fixatives are incapable of fixing themselves upon 

 more than a single species of bacteria or upon a single class of 

 animal cells, and only certain of them can fix themselves upon [579] 

 allied species or cells, such as the red corpuscles of several species 

 of animals. In these cases, too, there exists a sharp quantitative 

 difference between the fixation on the different formed elements. 

 The same microcytases are, on the other hand, able to attack all 

 kinds of micro-organisms, and the same macrocytases attack all kinds 

 of animal cells. 



We have seen that the cytases correspond to the zymase and to 

 the proteolytic diastase of the yeasts in the sense that all these soluble 

 ferments adhere with tenacity to the cells which produce them and 

 contain them. The fixatives, in this respect, approach sucrase 

 (invertin) : these various soluble ferments pass readily into the fluids 

 which bathe the cells that produce them. The fixatives are found 

 not only in the blood serums, prepared outside the body, but also in 

 the blood plasma, whence they pass into the fluids of the exudations 

 and transudations. Whilst no cytases are found in the subcutaneous 

 tissue, or in the clear fluids of oedemas containing no, or almost no, 

 cells, fixatives are not absent from these various situations just 

 indicated. For this reason, when micro-organisms are introduced 

 subcutaneously, they are not found to be altered by the cytases, 

 but it is easily seen that they are permeated with fixatives. The 

 same rule applies to the fixatives of the animal cells. In the 

 example we have cited, the spermatozoa, in an animal whose serum 

 renders these cells motionless, remain quite motile in the epididymis 

 and below the skin. From this fact it may be concluded that these 

 situations contain no free macrocytase. It is sufficient, however, to 

 add to these motile spermatozoa a drop of normal serum contain- 

 ing macrocytase to stop their movements at once, the fixative 

 being well distributed in the plasma of the living animal. The 

 spermatozoa, then, were sensibilised by the fixative which was found 

 in both the epididymis and in the subcutaneous tissue. 



The cytases are soluble ferments which are essentially intra- 

 cellular : the fixatives are, on the other hand, soluble ferments 

 which are humoral. These fixatives, however, although circulating 

 in the plasmas, are undoubtedly of cellular origin. This fact was 

 first demonstrated by Pfeiffer and Marx, who found the specific 

 fixative of cholera vibrios in the " haematopoietic organs," that is to 



