THE OUTLOOK 601 



knowledge is fundamental to our control of zymotic diseases. We find 

 that whereas to certain organisms we oppose an impenetrable resistance, 

 to others our resistance is very slight. Our acquired resistance, result- 

 ing from infection or artificial immunization, varies between the same 

 extremes. The transient or inappreciable immunity conferred by 

 immunization in many diseases lays us open continually to their 

 inroads with resulting loss of life and efficiency which have been 

 displayed upon a gigantic scale in the recent world-wide scourge of 

 influenza. The erection of defenses against such plagues, and the 

 common infections of the respiratory or alimentary tracts which are 

 responsible, in the aggregate, for so much loss of effort, time, life and 

 efficiency in the world, w r ill never be possible until we understand the 

 underlying chemical reasons why resistance, natural or acquired, to 

 this disease should be high and permanent and to that, slight and 

 transient, and our understanding of this will in turn depend upon the 

 acquirement of knowledge of the actual chemical nature of the anti- 

 bodies and the precise nature of the processes involved in their inter- 

 action with the tissues or toxins of the invading parasite. The study 

 of these substances and reactions is proceeding apace, and a clear and 

 full understanding of the mechanisms of immunity, while perhaps as 

 yet remote, will unquestionably be acquired. 



The conquest of zymotic disease has begun, many of the bitterest 

 scourges of the middle ages have disappeared from our lives never to 

 return, and one by one our parasitic enemies are being deprived of 

 power to mar or destroy our lives. Our disorders of function are 

 gradually becoming understood, chlorosis and gout are disappearing, 

 myxedema may be prevented, such conditions as cretinism and 

 asthma are being traced to avoidable origins, diabetes is coming under 

 control, and while cancer still exercises its ravages almost uncurbed 

 that dark problem too now presents some openings which the forth- 

 coming advances of our knowledge of the chemistry of growth will 

 undoubtedly enable us to convert into means of its eradication or 

 prevention; for the problems of pathological growth are fundamentally 

 identical with the problems of normal growth, and the information 

 which sheds light upon the one type of growth will reveal the origin 

 of the other. 



Senescence alone remains untouched, the final triumph of nature 

 over the human desire to live; but if we can once rid ourselves of the 

 suggestive influence of age-long experience and view the phenomenon 

 impersonally, as the culmination of a definite, understandable and 

 therefore controllable process, we. will perceive that this too must 

 ultimately, fall under the sway of human intellect. The indefinite 

 prolongation of his own life is the manifest destiny of man, and the 

 progress already achieved is certainly not less than that which had 

 been made toward our conquest of the air when Leonardo da Vinci 

 so confidently, and as it then seemed so futilely, predicted that man 

 would ultimately fly. 



