266 SECRETS OF ANIMAL LIFE 



got something quite definite to say something well 

 deserving to be thought over that the physiological 

 condition of the parents at the time of re- 

 production influences the next generation. What is 

 meant is not that two hard-set, thick-skinned, tough- 

 minded, and well-controlled parents are likely to 

 have children after their own image, or that two 

 slack, thin-skinned, flabby-minded, and feckless 

 parents are likely to have children after their kind; 

 for this would simply be the generally accepted 

 doctrine that innate constitutional characters are 

 entailed from generation to generation. Like tends 

 to beget like ; no grapes from thorns nor figs from 

 thistles. But what Mr. Bonhote means is something 

 different and something debatable. 



His argument is this. Changes or peculiarities in 

 environmental conditions (including food, warmth, 

 humidity, and so on) have an influence on the 

 physiological state of susceptible organisms. Corre- 

 sponding to the " nurtural " changes or peculiarities 

 there are often internal changes in the metabolism. 

 This is admitted by all biologists. But may it not 

 be that the character of the metabolism, environ- 

 mentally modified about the time of parentage, 

 reacts on the germ-cells and affects them in some 

 way, so that their development, i.e. their expression 

 of the inheritance, is different from what it would 

 have been if the parental constitution had not been 

 affected by the nurtural modifications? In the 

 author's terminology, which we cannot accept, the 

 altered vigor of the parents may affect the initial 



