PREFACE. 



AT an early period after the publication of the last part of the English 

 edition of Professor Miiller's Physiology, it became necessary to reprint 

 the second volume of the work; a second edition of the first volume 

 having already been issued. The second volume did not then need 

 complete revision and re-editing ; it was therefore reprinted with only 

 a few verbal alterations. But it was determined that, after a certain 

 lapse of time, there should follow a Supplement or Appendix, containing 

 later information on the subjects treated of in the most important portion 

 of the volume, namely, that portion comprising the Physiology of Ge- 

 neration and Development ; and reference was made to such an Appendix 

 in several pages of the reprinted volume. 



In accordance with this plan, I was occupied during part of the winter 

 of 1845-6, with preparing an account of the advances made in the course 

 of the previous three years in the departments of science just named, 

 but other unavoidable engagements interrupted my progress with the 

 undertaking at that time, and subsequently prevented me from resuming 

 it. The project, however, could not well be relinquished. Finding, there- 

 fore, a few months since, that I still was not able to command the re- 

 quisite leisure, I proposed to Messrs. Taylor and Walton that Dr. Kirkes 

 should be requested to lend his aid towards the immediate completion 

 of the work, a proposal to which they readily acceded. And Dr. Kirkes 

 very kindly consented to render the assistance required, although himself 

 engaged in the preparation of a separate Treatise on Physiology. 



It has been found advisable to extend the original plan of the present 

 work, and to make it supplementary to the entire second volume of 

 Professor Miiller's Elements of Physiology, by including an account of 

 the more important advances in the Physiology of Motion and of the 

 Senses. These departments of the science have not, however, been so 



M371701 



