part of the larger body. It is in effect a coordinating committee 

 representing the American Chemical Society, the American Society 

 of Bacteriologists, the Society of American Zoologists, the Botan- 

 ical Society of America, the American Association of Pathologists 

 and Bacteriologists and the American Association of Anatomists. 

 It has a membership of about sixty biologists, members of the 

 various societies just mentioned, who assist in the examination and 

 testing of stains, each in those particular lines of technic with which 

 he is especially familiar. It has secured the cooperation of chem- 

 ists, dye manufacturers and stain dealers, so as to be sure that the 

 needs of biologists can be immediately reflected in the supply of 

 stains on the market. Its affairs are managed by an executive 

 committee of five members, the present members of which repre- 

 sent bacteriology, botany, dye chemistry, pathology, and zoology, 

 respectively. This executive committee has undertaken the pre- 

 paration of this book. The authorship of the book has been as- 

 sumed by the chairman of the committee, however, in order to fix 

 the responsibility and to make bibliographic references to it 

 simpler than in the case of plural authorship; but the assistance of 

 the other committee members in the work has been so great that 

 they may be practically considered co-authors of the book. The 

 chairman of the committee, therefore, wishes to take this occasion 

 to acknowledge the invaluable assistance given by these other 

 members. Without their cooperation such an undertaking would 

 have been impossible. 



The chief object of the book is to present in logical form the in- 

 formation which has been accumulating in the hands of the Com- 

 mission since it was organized. It is neither a treatise on dye chem- 

 istry nor one on microscopy; altho it contains information in both 

 fields. It is an effort to present in a form acceptable to biologists 

 the principles of dye chemistry so far as they have a bearing on 

 biological stains; and to discuss the suitability of the different dyes 

 for various biological purposes, presenting data partly original and 

 partly drawn from the literature. The subject matter is realized to 

 be incomplete, particularly that part of it which deals with the 

 biological uses of dyes. An effort has been made to list the most 

 important present uses of stains, and of the obsolete uses to men- 

 tion those of historical significance; but it is realized that there must 

 be many omissions. It is hoped that readers of the book will co- 

 operate by calling to the author's attention places where the treat- 

 ment of any subject seems inadequate. 



H. J. Conn, Chairman, 

 Commission on Standardization 

 of Biological Stains. 

 Geneva, N. Y., 1925. 



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