320 GENERAL BIOLOGY 



decide between survival and extermination. (3) Al- 

 lowing for the fact that certain small variations are 

 advantageous to their possessors, and granting that 

 of the hosts of individuals born into existence, 

 but a minute fraction can hope to survive, yet in 

 many cases chance must play a larger part in their 

 extermination than the possession of any kind of 

 morphological or physiological character whatever. 

 (4) Most significant of all, perhaps, is the experimen- 

 tal demonstration that artificial (and by inference, 

 natural) selection has narrow limits. Beyond a 

 certain point (see p. 219) the pull of the mysterious 

 factor of regression prevents any further progress 

 in that direction. 



Critique of the Lamarckian Theory. The chief 

 characteristic of man as distinguished from other 

 animals is the fact that he " looks ahead " and shapes 

 means to his own ends. It is difficult to avoid 

 unintentionally attributing the same purposes to 

 the abstraction we call "Nature " or the "species." 

 Animals and plants react to many stimuli. Often 

 these reactions are advantageous and these we note ; 

 frequently they are quite the contrary, and these we 

 sometimes fail to remember. Man stores up food 

 to provide for a future time of want. When a potato 

 stores up starch in the tuber, what more natural 

 than to think of it in the same way, the plant is 

 anticipating its own needs ? But it has been dis- 

 covered that the formation of tubers is directly due 

 to the presence of an infecting fungus and does not 

 occur in its absence. 



