PREFACE 



WHEN microscopists first began, in the sixties and seventies, 

 to use stains, the demand for dyes for this purpose was 

 naturally too small to justify a special source of supply. 

 They therefore had to make use of textile dyes, which were then 

 very crude and were not constant in their composition. After a 

 number of years, however, the demand for biological stains grew 

 and a special commercial source of supply for them first appeared 

 in Germany. This was the Grl'ibler Co., later Griibler and Hol- 

 born. This company did not manufacture the dyes, as used com- 

 monly to be thought in other countries; but on the other hand it 

 cannot be denied that its founder made a distinct contribution to 

 science in making the first effort to secure constancy and reliability 

 in dyes intended solely for the use of the microscopist. It is sup- 

 posed that he tested dyes under the microscope himself, and if a 

 batch proved satisfactory in his experience bought a supply large 

 enough for a number of years, bottled it under his own label and 

 sold it to biologists. There is no question but that in this way the 

 biologist was furnished with a much more reliable line of stains 

 than if he had been obliged to buy directly from the dye manufac- 

 turers; but it was an empirical method of standardization and there 

 was nothing to prevent different batches of some dye secured by 

 this company from varying considerably in their composition. 

 Such upon investigation has proved to be the case. 



Altho a great service was done to biologists by this company in 

 the latter part of the nineteenth century, such methods of stan- 

 dardization are not in keeping with modern scientific knowledge. 

 A recent cooperative undertaking has therefore been organized in 

 America to put the standardization of stains upon a scientific basis. 

 This undertaking started after the war had caused a shortage of 

 stains, with the object of securing a reliable supply when the foreign 

 sources were unavailable. It has since then been widened in its 

 scope; and now that the foreign products are again available, the 

 purpose of the work is to effect a scientific standardization of 

 stains whether derived from foreign or domestic sources. As a 

 matter of fact, so far only domestic samples have been considered. 

 This has not been because of any prejudice against foreign stains, 

 but because of practical difiiculties; it is, in brief, difficult to test 

 each batch before it is put on the market when the concern handling 

 it is in Europe. 



The organization thru which this work is being carried on is 

 known as the Commission on Standardization of Biological Stains. 

 It was organized in 1922 under the auspices of the National Re- 

 search Council and is still affiliated with it, altho now no longer a 



