were available and microscopists were constantly finding new uses 

 for them. Gierke wondered if there would be any opportunity for 

 equal development during the ten years to follow his paper. 



That development did not stop in his day is well known. Scarcely 

 a year has passed without the introduction of some new staining 

 technic of considerable importance. Sometimes dyes hitherto un- 

 known to the biologist have been shown to be valuable in bringing 

 out some particular structure; at other times new combinations of 

 dyes have proved of special value for other purposes; while by 

 other investigators it has been shown that old methods, used with 

 modern refinements of apparatus and technic, may bring out details 

 not dreamed of by the early histologists. But the farther this work 

 has progressed the more the microscopist has become dependent 

 upon his supply houses to furnish him reliable stains, so carefully 

 purchased or manufactured that each lot ordered could be counted 

 upon to duplicate the last. 



The preface of this book describes briefly how a company was 

 formed in Germany to meet the demand for dyes for staining pur- 

 poses that developed during the last three decades of the nine- 

 teenth century, and how the recent post-war conditions, together 

 with the modern demand for a more scientific basis for the industry, 

 led to the establishment in America of a Commission on Stan- 

 dardization of Biological Stains. The work of the Commission is 

 two-fold. First, by cooperation of various biologists and chemists 

 it is planning to get together all the available information concern- 

 ing the nature of dyes as related to their use for various purposes in 

 microscopic technic ; secondly, by working with the manufacturers 

 it is trying to see that the supply of stains available in America is 

 of the highest possible qualit}^ as judged by their performance in 

 actual laboratory use. 



The first of these purposes has been partly accomplished by a 

 series of brief notes appearing in certain biological publications; and 

 is now being more fully reaHzed by the publication of this book. 

 The second object is being slowly brought about by the plan of 

 certifying stains. Manufacturers of stains are being encouraged to 

 submit to the Commission, for testing, samples of different batches 

 of their various stains. These samples the Commission compares 

 by chemical tests and by submitting them to several biologists 

 skilled in different lines of miscoscopic technic. Then in the case 

 of those samples which prove satisfactory, the Commission allows 

 the company to sell the batch tested with a label on it issued by 

 the Commission, bearing the statement: "Found satisfactory by 

 Commission on Standardization of Biological Stains for purposes 

 mentioned on main label. Use for other purposes not contra- 

 indicated unless specifically so stated on said label." This certi- 

 fication is issued only for the particular batch tested. The manu- 

 facturer is furnished only with enough labels to last for that batch 

 in the ordinary course of trade; and occasional tests of market 



10 



