4 GENERAL PROPERTIES OF LIVING TISSUES 



bring the phenomena of living matter within 

 the operation of chemical and physical laws 

 without recourse to the supernatural and occult. 

 According to this new, unified view of nature, 

 which is the foundation of modern physiology, 

 all phenomena, whether animate or inanimate, 

 are alike the expression of chemical and physi- 

 cal processes, some known, some unknown, none 

 of which is fundamentally different from the 

 rest. 



The physiologist, therefore, now looks upon 

 the reactions of living matter with the eye of 

 the physicist, and it is of the first importance 

 to beginners in physiology to acquire this point 

 of view. To this end it is desirable to consider 

 living tissues from the standpoint of energy and 

 to divide, even imperfectly, the functions to be 

 studied into those that have to do with the 

 income of energy and those that are active in 

 its outgo. These studies cannot, however, be 

 profitably undertaken without some acquaint- 

 ance with the general properties of living tissues, 

 such as irritability and contractility. 



We shall begin, therefore, by examining a 

 motor nerve and the muscle in which its fibres 

 are distributed. 



The Nerve-Muscle Preparation. Wrap the 

 frog in the cloth, the head out. Pass one blade 



