THE LIVING MACHINE BUILDING FACTORS. 193 



the weakest will go to the wall, while those that 

 are best adapted for their place in life will be the 

 ones to get food, live, and reproduce their kind. 

 This is at all events true among the lower animals, 

 although with mankind the law hardly applies. 

 Now, among the individuals that are born there 

 will be no two exactly alike, since variations are 

 universal, many of which are congenital, and thus 

 born with the individual, and transmitted by in- 

 heritance. Clearly enough, those animals that 

 have a variation which makes them a little better 

 adapted for the struggle will be the ones to live, 

 and hence to produce offspring, while those with- 

 out such advantage will be the ones to die. We 

 may suppose, for example, that some of the indi- 

 viduals had longer necks than the average. In 

 time of scarcity of food these individuals would 

 be able to get food that the short-necked indi- 

 viduals could not reach. Hence, in times of 

 famine, the long-necked individuals would be the 

 ones to survive. Now, if this peculiarity were a 

 congenital variation, it would be already repre- 

 sented in the germ plasm, and consequently it 

 would be inherited by the next generation. The 

 short-necked individuals being largely destroyed 

 in this struggle for food, it would follow that the 

 next generation would be a little better off than 

 the last, since all would inherit this tendency to- 

 ward a long neck. A few generations would 

 then see the disappearance of all individuals 

 which did not show either this or some other 

 corresponding advantage, and in this way the 

 lengthened neck would be added permanently as 

 a par t of the machine. When this time came this 

 N 



