4 PREFACE. 



has been made after a careful study of the original publi- 

 cation, any one acquainted with the literature of the ner- 

 vous system will appreciate the amount of labor involved 

 simply in bibliographical research ; but in this depart- 

 ment, more than in any other, it is necessary to avoid 

 taking experiments and opinions at second-hand. The 

 experience of many years, as an experimental physiolo- 

 gist and a practical teacher, has enabled the author to 

 verify many of the important facts stated in this volume, 

 and has led to some original observations, which appear 

 in the body of the work. 



The present volume treats of the physiological anatomy 

 and the functions of the nervous system, as they appear 

 to a practical physiologist, accustomed to accept nothing 

 that is not capable of positive demonstration or well-sus- 

 tained inference. Adhering conscientiously to the posi- 

 tive method of study, the author has endeavored to pre- 

 sent an account of the nervous system, which, though it 

 will undoubtedly.be extended by future investigations, is 

 made up mainly of statements of facts that will probably 

 not undergo serious modification, as we advance in our 

 knowledge of the subject. He has considered the proper- 

 ties and functions of the cerebro-spinal and sympathetic 

 nervous systems, mainly from this point of view ; and has 

 touched but slightly upon psychology, which has long 

 been considered a science by itself. The special senses 

 have been deferred, to be taken up in the fifth and last 

 volume of the series. 



The physiological anatomy of the nervous system is 

 regarded by the author as an indispensable preparation 

 for the study of its functions. The most reliable recent 



