HANDBOOK OF PHYSIOLOGY. 



CHAPTER I. 



THE PHENOMENA OF LIFE. 



HUMAK physiology is that part of animal physiology which treats 

 of man of the way in which he lives and moves and has his being. 

 It teaches how man is begotten and born; how he attains maturity, 

 and how he dies. 



As, however, man is a member of the animal kingdom, although 

 separated and specialized no doubt to a remarkable degree, he during 

 life manifests certain characteristics possesses certain properties and 

 performs certain functions in common with all living animals, even 

 the very lowest, and these may be called essentials of animal life. If we 

 go a step further, we find that most of these characteristic properties 

 and functions are possessed also by the very lowest vegetable structures, 

 and are in fact the characters by which we distinguish living from not- 

 living matter; they are essentials or phenomena of life in general. Thus 

 we see that as human physiology, which treats of man only, is a part of 

 animal physiology, which treats of the functions and organization of 

 animals in general, so is animal physiology but a part of the wider 

 science of Biology, which embraces the organization and manifestations 

 of all living things. 



Before entering upon the study of Human physiology, therefore, it 

 is useful and even necessary to devote our attention for a little while to 

 the investigation of what are the properties and functions common to all 

 living matter, and how they are manifested, since it would be unwise to 

 attempt to comprehend the working of the complex machine of the life 

 of man without some knowledge of the motive power in its simplest 

 form. 



Living matter, in its most elementary form, is found to consist of a \ 

 jelly-like substance which is now generally known under the name of 

 Protoplasm. 



This substance, in its most primitive form, and in minute masses, is 

 found undifferentiated and perfectly homogeneous, and constitutes the 

 lowest types both of animal and vegetable life that can be observed 

 1 



