CH. XIX Influence of Habits and Surrmmdings 307 



logical prism. Thus we try to analyse the light of life. But 

 inheritance in its widest sense is only another name for the 

 organism itself, and function is simply the organism's activity. 

 The organism is real ; the environment is real, in it we live 

 and move ; function consists of action and reaction between 

 these two realities. Yet the capital which the organism 

 has to begin with is verj' important ; conduct has some 

 relation to character, and function to structure ; the sur- 

 roundings — the dew of earth and the sunshine of heaven 

 — silently mould the individual destiny. 



A living animal is almost always either acting upon its 

 surroundings or being acted upon by them, and life is the 

 relation between two variables — a changeful organism and 

 a changeful environment. And since animals do not and 

 cannot live in vacuo, they should be thought of in relation 

 to their surroundings. You may kill the body and cut it to 

 pieces, and the result may be interesting, but you have lost 

 the animal just as you lose a picture if you separate figure 

 from figure, and all from the associated landscape or interior. 

 The three Fates are sisters, they are thoroughly intelligible 

 only as a Trinity. 



The most certain of all the relations between an organism 

 and its surroundings is the most difficult to express. We 

 see a small whirlpool on a river, remaining for days or 

 weeks apparently constant, with the water circling round 

 unceasingly, bearing the same flotsam of Leaves and twigs. 

 But though the eddy seems the same for many days, it is 

 always changing, currents are flowing in and out ; it is the 

 constancy of the stream and its bed which produces the 

 apparent constancy of the whirlpool. So, in some measure, 

 is it with an animal in relation to its surroundings. Streams 

 of matter and energy are continually passing in and out. 

 Though we cannot see it with our eyes, the organism is 

 indeed a whirlpool. It is ever being unmade and remade, 

 and owes much of its apparent constancy to the fact that 

 the conditions in which it lives — the currents of its stream 

 — are within certain limits uniform. 



But as we cannot understand the material aspects of an 

 animal's life without considering the streams of matter and 



