PREFACE. 



THE collaboration of several teachers in the preparation of an elementary 

 text-book of physiology is unusual, the almost invariable rule heretofore 

 having been for a single author to write the entire book. It does not seem 

 desirable to attempt a discussion of the relative merits and demerits of the two 

 plans, since the method of collaboration is untried in the teaching of physi- 

 ology, and there is therefore no basis for a satisfactory comparison. It is a fact, 

 however, that many teachers of physiology in this country have not been 

 altogether satisfied with the text-books at their disposal. Some of the more 

 successful older books have not kept pace with the rapid changes in modern 

 physiology, while few, if any, of the newer books have been uniformly satis- 

 factory in their treatment of all parts of this many-sided science. Indeed, the 

 literature of experimental physiology is so great that it would seem to be 

 almost impossible for any one teacher to keep thoroughly informed on all 

 topics. This fact undoubtedly accounts for some of the defects of our present 

 text-books, and it is hoped that one of the advantages derived from the col- 

 laboration method is that, owing to the less voluminous literature to be 

 consulted, each author has been enabled to base his elementary account upon 

 a comprehensive knowledge of the part of the subject assigned to him. Those 

 who are acquainted with the difficulty of making a satisfactory elementary 

 presentation of the complex and oftentimes unsettled questions of physiology 

 must agree that authoritative statements and generalizations, such as are fre- 

 quently necessary in text-books if they are to leave any impression at all upon 

 the student, are usually trustworthy in proportion to the fulness of informa- 

 tion possessed by the writer. 



Perhaps the most important advantage which may be expected to follow 

 the use of the collaboration method is that the student gains thereby the point 

 of view of a number of teachers. In a measure he reaps the same benefit as 

 would be obtained by following courses of instruction under different teachers. 

 The different standpoints assumed, and the differences in emphasis laid upon 

 the various lines of procedure, chemical, physical, and anatomical, should 

 give the student a better insight into the methods of the science as it 



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