10 LIVERPOOL BIOLOGICAL SOCIETY. 
always having reference to some general end :—‘‘the 
function of respiration, for example, including the actions 
of many different organs, all of which co-operate in 
effecting some necessary change in the composition of 
the fluids. In this view of the matter, then, a function 
may be defined to be the action, not of an Organ but of 
an Apparatus destined to some specific purpose in the 
general economy of an organised being.’’* Now the 
possession of any apparatus, however simple, implies 
structure and the manifestation of varrous physical and 
chemical actions to which the term vital could never be 
apphed. For example, in a vertebrate animal with motor, 
circulating and digestive apparatus, the resistance and 
support of the skeleton and the tenacity and elasticity of 
the blood-vessels are physical attributes, but the formation 
and maintenance of these and all other tissues are vital. 
The first stages of the digestion of food are mere chemical 
action, but the secretion of the digestive ferments and 
juices, the absorption of the chyme by the villi, and the 
conversion of it into blood are vital. The perception of 
stimuli and discharge of vis nervosa are vital, but the 
transmission of it through the nerves is probably physical. 
The whole quantitative relations of the transformation of 
force in living beings are exactly the same as in non-living 
things. From this it is evident that the functions are 
composed of both living and non-living actions. 
Besides this, we have seen that the second factor of the 
production of life, according to John Brown, includes not 
only ‘‘ external agents,’ but ‘‘certain functions peculiar 
to themselves” (acting as stimuli to other parts), these 
together comprising what is now termed the environment. 
The environment is always non-living, and a portion of 
it is a part of each living individual. ‘Therefore we 
* Fletcher’s ‘‘ Physiology,” vol. ii., p. 5. 
