CHAPTER III 

 ORGANIC FUNCTIONING 



By the term Behaviour is meant all the ordinary activities, and 

 chiefly motions, of the living animal considered as a unitary 

 thing. Thus its locomotions, actions of aggression and defence, 

 the pursuit and capture of its prey, the seeking of shelter, making 

 nests, the construction of artifacts, its play and courtship, etc., 

 are examples of behaviour. 



The limbs, wings, fins and other bodily appendages, the jaws, 

 teeth, claws, spines, etc., are the agents of behaviour. These 

 agents are actuated by systems of muscles, which are attached 

 in various ways to bones and other relatively rigid parts, on the 

 one hand, and to the movable instruments of behaviour (as the 

 human hands and fingers) on the other. The muscles can be 

 thrown into states of tension so that forces are applied to the 

 instruments of behaviour. Such forces are initiated and regulated 

 by the central and peripheral nervous systems, by the organs 

 of sense and by the experience of the animal (see further in 

 Section 39). 



The instruments of behaviour are mechanisms of skeleton, 

 muscle and nerve : These w^e may call action- systems and their 

 forms depend on the general structural plans of the animals 

 considered. 



The action-systems are energized by the organs of alimentation, 

 respiration and circulation — that is, by all the mechanisms that 

 digest and assimilate food materials — thus obtaining substances 

 that have energy ; by the oxygen taken into the body and by 

 the heart and blood-vessels that distribute these materials through- 

 out the body. Further metabolic organs preserve a general balance 

 in the chemical constitution of the body. 



Thus w^e may speak of the energizing system, and the metabolic 

 system of bodily organs. The general activities of these parts 

 may be called organic functioning : this is, of course, subservient 

 to behaviour. 



55 



