36 Biological Stains 



stain Hofmann's violet. Then a third laboratory worker may redd 

 both articles and wish to try both methods; so he accordingly 

 orders both dahlia and Hofmann's violet. His dealer, who may 

 be unacquainted with dyes, will very likely send him a bottle bear- 

 ing each name, and the purchaser has no easy way of discovering 

 that the two are identical; so he may continue for years to use the 

 two stains for different purposes, misled by their labels and think- 

 ing them distinct. The manufacturers and dealers in stains have 

 sometimes encouraged this confusion by their practice of taking 

 care to have the label on the bottle agree with the name used in 

 the customer's order, regardless as to what the usual name for the 

 dye may be. 



An attempt to relieve this confusion has been made by the Com- 

 mission on Standardization of Biological Stains (1923f) by publish- 

 ing a list of biological stains with their best known synonyms. In 

 each case one of the names is listed as a preferred designation. 

 Sometimes general usage made it easy to select one name as the 

 preferred one; but in other instances the selection was more or less 

 arbitrary. This same list, with a few revisions in the way of ad- 

 ditions and corrections, is given in the appendix of this book (p. 

 252; see p. 106 of first edition). A few new stains have been 

 added to this list, but essentially it is the same as published in 

 1923. The chief changes have been in the list of synonyms, which 

 has been* revised to omit names that are obsolete and have no 

 present meaning. With but one or two exceptions the preferred 

 designations are still the same as in the first list. 



DYE INDEXES 



There have been two important indexes of dyes, one published 

 in Germany (Schultz' Farbstofftabellen) the other in England (the 

 Colour Index of the Society of Dyers and Colourists). Seven edi- 

 tions of the former appeared up to the time of the second World 

 War, while only one edition (1923) has yet appeared of the latter. 

 It was natural that the earliest efforts to index dyes should have 

 been made in Germany as there was almost no dye industry out- 

 side that country until 1914; but the 1923 edition of Schultz was 

 so much less complete than the Colour Index which came out the 

 same year that there has been a recent tendency to follow the latter 

 rather than the former. In the second edition of the present book, 

 therefore, the Colour Index numbers of the various dyes were listed 

 instead of the Schultz numbers. 



The seventh Schultz index was as complete as the Colour Index, 

 with an entirely new system of index numbers assigned to the dyes, 

 agreeing neither with that in the other publication nor with earlier 

 editions of Schultz. Considering how often it is desirable to refer 

 to a dye by an index number, it is unfortunate that these numbers 

 cannot be standardized in some way by international agreement. 



