604 THE CONTROL OF LIFE: 



from out of a crab-apple all the treasures of the orchard, 

 may he not replace sourness by sweetness in human char- 

 acter ? If Man can evolve from out of a wolf-like creature 

 the domesticated dog, the trusty guardian of his flocks, may 

 he not hopefully try to evolve the wolfish out of mankind ? 

 A few Darwinians were indeed inclined to be too sanguine, 

 overlooking the fact that all that Man did in his domestica- 

 tion and cultivation was to use with discretion the varia- 

 tional material which the organisms themselves put into his 

 hands. 



Moreover, investigation brought to light many instances 

 of marked modifiability. So much can be done by training, 

 by exercise, by dieting, by altering the surroundings that 

 we cannot wonder that there was for a time an exaggeration 

 of the transforming power of function and environment. The 

 fact is, however, that what is expressed from within is much 

 more important than what is impressed from without; the 

 range of variability is much wider than that of modifiability. 

 Moreover, we do not know that the individually acquired 

 modifications of the parents can be entailed as such or in 

 any representative degree on the offspring. 



It was pre-eminently Pasteur who made the idea of con- 

 trollability glow. He may be taken as type of the many 

 illustrious investigators who have been inspired to great 

 achievements by the idea of the biological control of life. 

 Beginning with measures for getting rid of the silkworm 

 disease, which was ruining the south of France, Pasteur 

 proceeded to attack such terrible scourges as splenic fever 

 and hydrophobia, and conquered by understanding them. 

 With object-lessons on a grand scale he convinced every 

 open mind that the days of folded hands and resignation 

 were over, and that it was for Man, with Science as torch, 



