AUTHOR'S PREFACE. 



I HAVE once more subjected this book to a thorough 

 revision, and endeavoured to incorporate in it the results 

 of all important recent work in the widening physiological 

 field. In so doing, I have tried to keep in mind that the 

 book is a student's text-book, and that it is therefore neces- 

 sary not to overwhelm its readers with a mass of unnecessary 

 detail. The introduction of new matter entails the excision 

 of what is antiquated or unnecessary, and so I have been 

 able to keep the size of the work pretty much as it was. 

 The present edition exceeds its predecessor by only fifteen 

 pages, and this increase is largely due to the fact that about 

 twenty new illustrations have been added. It is impossible 

 to enumerate all the changes now introduced, for hardly a 

 page has escaped some alteration. The principal additions 

 are, however, as follows : New sections have been intro- 

 duced on the significance of Nissl's granules, on Waller's 

 work on the electrical currents of the eyeball, on Cannon's 

 researches in connection with stomach movements, and on 

 Waymouth Reid's investigation of the processes of absorp- 

 tion. The sections relating to the electrical phenomena 

 of muscle, to the proteids, to the ductless glands, to the 

 muscles of the larynx, to the cranial nerves, and to 



