132 



CHAL'TKli XI. 



p. 251; Zeit. f. iviss. Mile, xvi, ;i, 1899, p. 223; Jouni. Roy. Mic. Soc, 

 1899, p. 547 ; Encycl. mik. Tt'cUiiih, 1903, p. 1028 ; Pappbnhbim, op. cit. 

 supra; Heidenhaim", Anat. Ann., xx, 1901, p. 36, 



204. The Chromatophily of Tissue-Elements.— The elements 

 of tissues are distinguished as " basophilouf:/' " acido- 

 philons," and "neutrophilous," according as they seem to 

 show a natural affinity for basic, acid, or neutral colouring 

 matters. respectively According to a generalisation due to 

 Bhkltch [Zeit. Miu. Med., 1, 1880, p. 555 ; Eeicheet and 

 Du-Bois Reymokd's Arch. Anat. Phys., Phys. Ahtli., 1879, p. 

 571), the basic colours are in general chi*omatin stains — that 

 is, they have a special affinity for the element of nuclei 

 known as chromatin, so that they are mostly sharp nuclear 

 stains, and chromatin is hasppJdlons. The acid colours, on 

 the other hand, are, according to him, in general plasma 

 stains — that is, they have a special affinity for cytoplasm and 

 intercellular substances, which are therefore acidophiloiis . 

 The neutral colours exhibit special affinities for certain cell- 

 contents, and the elements affected by these are" said to be 

 neidro'pMlous. 



I think that that is a generalisation which requires some 

 explanation and qualification. In practical histology we 

 have to take account not only of the affinities for dj'es of 

 cellular elements in a physically and chemically iinaltered 

 state, but of the alterations in these affinities brought about 

 by the action of fixatives and mordants. Now most fixing 

 agents either diminish or increase the chromatophily of 

 tissues ; so also do all mordants, some of which may 

 even invert the natural chromatophily of tissues (see §§ 205, 

 207). Then, too, we have to take account also of the 

 resistance of the stain to the liquids employed for washing, 

 for dehydration, for clearing ; in short, we have to take into 

 account the way in which the dye behaves when employed 

 as a regiessive stain (§ '209). This is of peculiar importance 

 in the case of the coal-tar colours, seeing that they are 

 hirgely used for the regresiive staining of sections destined 

 to be dehydrated by alcohol and mounted in balsam. JSTow 

 Ehrlich's experiments take no account of these conditions. 

 (He worked with "cover-glass preparations" of isolated cells, 

 such as blood and lymph cells, and was thus able to avoid 



