14 THE CONTROL OF LIFE 



science which has led to the new metallurgy, to the 

 understanding, for instance, of what happens when parts 

 of a machine suffer from ' fatigue-stress,' and to a 

 discovery of how this may be prevented. Many illumin- 

 ating instances will be found in the essays entitled 

 Science and the Nation (Cambridge University Press, 

 1917). 



In the realm of organisms, as in the domain of things, 

 Science is giving man more control. Thus the progress 

 of the science of heredity has supplied levers which can 

 be used with great practical effect in regard to cereals, 

 root-crops, and fruits, cattle, sheep, and poultry. To 

 the interesting problems of forestry, which are of great 

 importance from the occupational as well as from the 

 economic side, the methods of genetics and bionomics 

 have only begun to be applied. Professor Oliver and 

 others have shown how ' waste places,' like sandy 

 heaths, pit-heads, and salt marshes, may be made 

 profitable. (See The Exploitation of Plants. Edited 

 by F. W. Oliver. London, 1918.) And there are many 

 other points d'appui. It may be that some discovery 

 in biochemistry will change the whole economic problem 

 of food-supply. 



In the next chapter we shall illustrate other aspects 

 of the rapidly growing biological control of life. Here 

 it must suffice to mention the conquest of many microbic 

 or parasitic diseases, from malaria to bilharziasis ; the 

 development of serum therapeutics, so important in 

 connection with diphtheria and tetanus ; the utilisation 

 of the secretions of the ductless glands of other organisms 



