26 



2. FUNCTION AND ACTIVITIES IN RELATION TO ENVIRONMENT 



We have just noted that from the point of view of structural adapta- 

 tion, structure cannot be separated from function. It is equally true 

 that from the point of view of physiology, function and behavior cannot 

 be separated from structure. 



Turning again to the black bass, which we have already used to 

 illustrate some points, we note that for the simple act of swimming, the 

 digestive tract, gills, heart, blood-vessels, brain, and muscles are neces- 

 sary. They must all be present to furnish the animal with the necessary 

 energy and impulses to make motions for swimming. It is obvious that 

 there is a division of labor between the different organs, and if any of 

 them are impaired or injured, or interfered with, the work cannot go on 

 in its proper manner, or perhaps not at all. The organism is a complex 

 of correlated parts and processes. If we interfere with any of these, e.g., 

 the circulation of the blood of the fish, which might be done in many 

 ways, the whole system of interdependent processes is interfered with. 

 The fish is a highly organized animal, but the same general laws of 

 relations of processes, such as respiration, circulation of food materials, 

 digestion, etc., apply to animals in which there are no special or definite 

 organs to take care of each separate process. The interdependence of 

 processes in the organism is sometimes called physiological proportionality 

 (370), i.e., the work accomplished by any one set of organs or processes 

 is proportional to that of another set or all the sets of processes in the 

 organism. When the processes are going on in perfect accord and in 

 proper proportionality, the organism is said to be in physiological equilib- 

 rium. The conception of the organism stated above may best be used 

 in considering the relations of animal activities and functions to the 

 environment. 



It is generally held that the various animal forms are made up of 

 different kinds of protoplasm and that the eggs of no two species are 

 alike as to protoplasmic character. They may differ only slightly in 

 appearance, as for example the eggs of a frog and of a salamander, but 

 even if the eggs of these two animals are laid in the same pool at the 

 same time, and the conditions are essentially the same surrounding the 

 two masses, one mass of eggs develops into frogs and the other into 

 salamanders (43, p. 8). The only logical conclusion is that the composi- 

 tion or protoplasm of the eggs is different. 



It must be noted at the outset, therefore, that different organisms are 

 made up of different kinds of protoplasm; furthermore, combinations of 



