40 Heredity, Variation and Genius 



characters are inherited ; for it is not unlikely that 

 their origins are to be found in obscure adaptive 

 responses to the conditions of the environment 

 which are transmitted. 



That two complex human germs, modified and 

 qualified as such germs have been by successive 

 combinations through countless generations, in- 

 heriting withal qualities dating from the very 

 beginnings of life, can in combining produce varia- 

 tions without end is easily imaginable, but how 

 could the two primal cells from which the count- 

 less millions of living creatures originally sprang 

 acquire such infinite possibilities of variation ? 

 When the primitive unicellular organism divided 

 into two equal halves and these halves divided in 

 their turn, and so continuously onwards, a series 

 of equal divisions and subdivisions might have 

 gone on unchanged world without end had there 

 been no change in the descendants. But inas- 

 much as the divisions could hardly always, if 

 ever, be exactly equal, no two things on earth 

 being exactly equal, and those which survived in 

 the struggle for existence had sometimes to adapt 

 themselves to different external conditions — and 

 the least imaginable external change would not 

 fail to cause a suitable reaction — they necessarily 

 acquired individual peculiarities, transmitting these 

 when they divided, and so started the variations 

 which multiplied to build the multicellular orga- 

 nism. Here then was a direct transmission of 

 acquired characters : the first differentiations 



