PEE FACE. 



THE modern development of Physiology has been 

 largely due to the application to this branch of science 

 of physical and chemical principles and laws. Physics 

 and chemistry are now constantly appealed to for aid 

 in working out physiological problems ; and the 

 physiologist finds himself continually resorting to 

 physical methods and apparatus, both for purposes of 

 illustration and research. In some respects, therefore, 

 the study and the teaching of Physiology have become 

 increasingly difficult because of the broadening of its 

 relations with other sciences. 



In the teaching of the subject at the University of 

 Glasgow the want has been felt of a small text-book 

 for students, in which the elementary facts and prin- 

 ciples of physics might be given together with their 

 physiological applications, and in which might be in- 

 cluded some detailed description of physical apparatus 

 and methods as adapted to physiological purposes. 

 To meet this want to some extent, a series of weekly 

 demonstrations was given by me to the students 

 attending the class during the winter months ; and 

 one of the results of that series is this text-book. 



