686 INTERNAL SECRETIONS AND PRESERVATION OF LIFE. 



1. The granules which constitute the secretion of all varieties 

 of leucocytes are the products of a continuous reaction in the 

 nucleus, in which the nuclein of its nucleus, the materials ingested 

 by the cell, and the plasmatic oxidizing substance and alkaline 

 salts take part. 



2. When a leucocyte becomes functionally incompetent it is 

 destroyed by oxidation in the blood-plasma. 



CLASSIFICATION OF LEUCOCYTES. We have proceeded as 

 far as we could with our analysis of the leucocytes as a unit, and 

 it now becomes necessary to ascertain, if possible, the functions 

 of the various types which histologists, headed by Ehrlich, have 

 established with the aid of staining methods. 



Kanthack and Hardy 16 not only give a clear, though suc- 

 cinct, outline of the various varieties of cells, but they empha- 

 size features of the problem which are of special interest to 

 us. After briefly reviewing the more prominent contributions 

 to our knowledge of the subject since Wharton Jones's me- 

 moirs, published in 1846, including the investigations of Kind- 

 fleisch (1863) and Max Schultze (1865), appeared, they write 

 as follows: 



"After Max Schultze, no further advance was made or, 

 indeed, was possible in the histological analysis of the sporadic 

 mesoblast, until Ehrlich, in 1878, furnished a rational basis 

 for the use of staining reagents by his far-reaching discovery 

 that the elective affinity of certain constituents of tissues for 

 particular stains could be referred to two factors: the chemical 

 nature of the staining substance employed and a point too 

 often neglected by workers who have followed his methods 

 the nature of the medium in which the stain is dissolved. 17 

 Ehrlich drew particular attention to the granules, the pos- 

 session of which characterizes various forms of wandering cells. 

 These, he divided into five classes, differing either in their 

 special affinity for bases, acid, or neutral dyes, or in size. The 

 a or eosinophile granulation colors only with acid dyes; the /3 

 granulation colors with both acid and basic dyes (amphophile); 

 the y granulation colors only with basic dyes, and the individual 

 granules are large; the $ granulation colors only with basic 



18 Kanthack and Hardy: Loc. tit., p. 82. 

 17 All the italics are our own. 



