PREFACE. ix 



Gscheidleii's Physiologisclie Metliodik, and Cyon's 

 Methodik der Physiologischen Experimente. 



Most of the woodcuts have been prepared by 

 Mr. Stephen Miller, of Glasgow, whom I have to 

 thank for the carefulness and accuracy of their 

 execution. 



I must also express my gratitude to Mr. Andrew 

 Gray, now Professor of Natural Philosophy in the 

 University College of North Wales, who very kindly 

 read the first part of the book, and suggested altera- 

 tions. 



I am conscious that the book as finished does not 

 reach even the level of my own hopes. I trust that, 

 at least, no errors or inaccuracies have been over- 

 looked in the revision. 



J. M'G. K 



Physiological Laboratory, 



University ) September, 1884. 



