322 THEORETICAL BIOLOGY 



surrounding-world. It never creates this surrounding-world, 

 but, through selection, binds it, by all its pegs and sockets, 

 into a unified casting-mould, which intimately embraces the 

 organism and its receptor and effector functions. 



This mould is the life-tunnel, constructed entirely from 

 indicators arranged in space and time. Here the existence 

 of the animal is passed, consisting as it does, not merely of 

 struggle, but of all the functions of the life. 



It is the task of biology to seek for the plans of the life- 

 tunnels, and to investigate the complicated ways in which 

 they intersect. 



The plan for each life-tunnel is fixed, and so is the creature 

 within it that takes on shape and power to move. But the 

 carrying out of the plan depends on external circumstances, 

 which always induce deviations. These deviations bear a 

 delusory resemblance to the variability of organisms, and 

 for the theory they are of secondary importance, although they 

 may come into the life of the individual and determine it. 



It was reserved for Darwin to make what is secondary of 

 primary importance, and simply to deny the main feature, 

 namely the definite plan. By doing this he secured the 

 recognition of physics and chemistry, but he wrecked his own 

 science, biology. 



The entire plan of an organism, which surrounds both it 

 and its life-tunnel, is only a part of the plan of the species, 

 which unites related organisms into a whole of a higher order. 



The introduction of the plan of the species, which, as the 

 consequence of sex, brings together into one common life the 

 confusing abundance of separate lives, helps us to understand 

 the manifold deviations of the individual plans, which in the 

 species flow together into a whole that expresses plan. We 

 are then faced with large organisms, stretching through long 

 periods of time and across large spaces, organisms whose 

 parts, the individuals, are fitted into one another. It is true 



