112 Stains and Staini)ig (chap. 10) 



the surface of the tissue by selective adsorption and then enter into 

 combination Avith the tissue. The proteins, nucleic acids, and other 

 components of the protoplasm proceed along lines of chemical laws by 

 exchanging ions. The Stearns (1929, 1930) maintain that tiie confusion 

 lies in the term adsorption, that it may be either a chemical or a physical 

 force, and the adsorbent can form ions and then proceed along chemical 

 lines. 



In any case, the staining properties depend on these three factors: 



1. strength of dye 



2. rate of ionization of tissue proteins and dyes 



3. pH value of dye solution and tissue proteins 



In addition, staining can be affected by other conditions: 



1 . alcoholic or aqueotis solution of dye 



2. low or high temperature during reaction 



3. simple or multiple combinations of dyes 



4. strong or weak concentration of dye in solution 



Standardization of Stains 



In the early days of tissue staining it was difficult to secure reliable 

 dyes. The textile dye indtistry was the sole source of dyes and products 

 received were often unsatisfactory. Standardization was crudely done as 

 to color, and this was no standardization as to chemical content. The 

 impurities were extremely variable in qtiantity and quality. Griibler in 

 Germany ^vas the first to try to standardize dyes and he built a highly 

 specialized business in this field. He did not acttially manufacture dyes, 

 biu he bought up batches from other firms and tested them for technical 

 use. After the beginning of the tAventieth century, certain events 

 changed Griibler's hold on the business of standardization. Perhaps of 

 greatest influence were two world wars, causing Germany to lose its 

 monopoly in the dye indtistry. No country could afford to remain de- 

 pendent on another coturtry for its sotirce of dye if that country was 

 likely to remain an enemy. 



The lack of German dyes led to a new form of standardization in the 

 United States. A body was organized called the Gommission on Stand- 

 ardization of Biological Stains, later to become the present Biological 

 Stain Commission. The object of this commission is to work with the 

 manufacturers showing them Avhat the biologists require, testing their 

 products and permitting approved batches to be put on the market with 



