54 PROBLEMS OF EVOLUTION 



may be strengthened by singing, or by systematic breathing 

 exercises. The voice will become much stronger if constantly 

 used in the proper way. Wonderful perfection in the co-ordina- 

 tion of muscles may be achieved by practice, with the result 

 that athletic records, deemed insuperable, may be "cut." But 

 how if we wish to originate a new organ ? Without engaging in 

 any definite speculations as to the mammalian pedigree, we may 

 feel sure that there was a time when the ancestors of mammals 

 had no limbs, nor even continuous fins from which limbs were 

 to develop. How can you exercise what does not exist ? On 

 Lamarckian principles you can, in theory, account for the improve- 

 ment and specialisation of a limb as the generations go by. But 

 when it is a question of the origination of any organ, the theory 

 collapses, even if we allow the big assumptions that are made. 

 How did the sense of hearing begin ? Exercise failing us, we 

 have to fall back on external conditions. This means that 

 sound striking against the skin stimulated it to sensitiveness 

 and developed the requisite nerves. If it could be so stimulated, 

 it must have already been sensitive, must have already possessed 

 some rudimentary acoustic machinery. This is the conclusion at 

 which we arrived before, that external conditions can originate 

 nothing. We find now that the same thing is equally true of 

 exercise ; it is only a stimulus to which the organism responds ; 

 it can help a man to attain the maximum development of brain or 

 body of which he is capable. It can give him nothing that was 

 not potentially his at birth. 



Exercise Any one who has read this chapter thus far will see what 

 growth importance Lamarckians attach to exercise. Its importance for 

 certain purposes is difficult to over-rate, but it is easy to show 

 that it cannot be made to serve the purpose of the Lamarckian. 



To begin with, growth in many cases proceeds entirely 

 without exercise. In the vegetable kingdom, if we except 

 certain minute forms of life which the drift of biological theory 

 may any day sweep into the animal world, there is no such thing 

 as exercise. The tree stands motionless and grows. Its sap 

 flows, but there is nothing that we can reasonably call exercise. 

 The minute diatoms protrude tongues of protoplasm and so 



