8 IXTliODUCTIOX. 



tilted under the name of " Jfinute Anatomy^' to designate those 

 morphological studies which are specially concerned with the inves- 

 tigation of the minute or microscopic structures and tissues of which 

 living beings are composed, apart from the grosser and more palpable 

 features of form and structure. 



Physiology. — In its broadest sense, Physiology may be stated 

 to be the science of life and vital phenomena, — understanding by 

 " science," knowledge methodised and reduced to its principles. In 

 other words. Physiology deals with ihxi functions exercised by living 

 , bodies, or by the various definite parts or "organs" of which most 

 living beings are made up. Morphology teaches us the structure of 

 ' the animated machine ; Physiology shows vis what the machine can 

 do, and what are the use and purpose of the various parts of which 

 the machine is composed. 



The study of the functions discharged by the human organism 

 constitutes a, distinct branch of Physiology to which the name of 

 Human Physiology is applied ; whilst Comparative Physiology is con- 

 cerned with the study of the vital phenomena exhibited by the lower 

 animals. 



All the vital actions of the organism — in other words, all physio- 

 logical phenomena — may be roughly divided into the following three 

 groups : — 



1 . Functions of nutrition, comprising the various functions by which 

 the organism is enabled to live, grow, and maintain its existence as 

 an iiidivichial. 



2. Functions of reproduction, comprising those fvmctions whereby 

 fresh individuals are produced, and the perpetuation of the species is 

 secured, whilst the original individual perishes. 



3. Functions of relation, comprising all those functions (such as 

 sensation and the power of voluntary movement) whereby the outer 

 world is brought into relation with the organism, and the organism 

 in turn is enabled to react upon the outer world. 



, The functions of nutrition and reproduction are essential to bare 

 existence, and are sometimes spoken of collectively as the " vegeta- 

 tive " functions, as being common to animals and plants alike. On 

 the other hand, the functions of relation are often spoken of as the 

 " animal " functions, since they are most highly developed in animals. 

 Various plants, however, are endowed with the power of movement, 

 and exhibit sensibility ef(ual in amount and apparently similar in 

 kind to that manifested by many of the lower animals ; so that the 

 functions of relation, though more characteristic of animals than of 

 plants, are not peculiar to animals. 



It should also be borne in mind, that though the above grouping 

 of the physiological functions is convenient, it is to a certain extent 



