WERNER MARCHAND 5 



have all the facts on a definite subject concentrated in one publication. 

 I have therefore decided to give not only a summary of the literature 

 with the bibliography, as is usually done in text-books, but also a 

 complete report of all the facts found in these publications, with very 

 little change in the wording, literal quotation of all authentic descrip- 

 tions, and with the reproduction of practically all the existing illus- 

 trations on the subject, sufficiently accurate to make the consultation 

 of the originals unnecessary. By this means I hope to relieve the 

 worker on the subject in question of the necessity of consulting 

 libraries, except the future monographer of the whole group, who will 

 prefer to go back to the original pubhcations. On the other hand, 

 as a full bibliography is given, in case of uncertainty about any detail, 

 the originals can always be consulted and compared with this report. 



There is, however, another consideration of some importance which 

 has guided me in preparing this review; that is, the desirability of 

 having, generally, all the facts on one subject of research concentrated 

 in one language, preferably English. The diversity of languages is a 

 great hindrance for the progress of science, and from the point of 

 view of methodical unification, specialists in any branch of science 

 should be encouraged to concentrate all the literature on their own 

 subject in the language which they prefer to have used. Having 

 given considerable time to the study of this question, I cannot see 

 any serious objection to the more general adoption of English in 

 science. It is to be hoped that the temporary disadvantages to the 

 non-English-speaking scientists, resulting from its adoption would be 

 made up by the advantages of a great progress in science which would 

 undoubtedly follow. It is for the scientists of English-speaking 

 countries to pave the way, by conquering the field systematically, 

 subject after subject, and to facilitate the production of new work 

 by a complete assimilation of work previously done in foreign 

 languages. 



I wish to express my indebtedness to the authorities of the American 

 Museum of Natural History and of the Philadelphia Academy of 

 Natural Science for giving me liberal access to their libraries and 

 collections, and to Dr. Theobald Smith, Director of the Department 

 of Animal Pathology under whose guidance this work was rendered 

 possible. 



