82 THE POPULAR SCIENCE MONTHLY. 



not to interfere so as to destroy the course of natural compensa- 

 tions ; but seeks by dietetical, hygienic, and climatic influences, 

 here by the removal of excitants, there by methodical stimula- 

 tion of the matter-changes of the nervous system to put the 

 organism into a condition to overcome the pathological disturb- 

 ances. To use such measures, carefully adapted on principles of 

 scientific observation and enlarged knowledge of the course of 

 disease to the most diverse conditions, continually to furnish a 

 closer support to the natural compensations and adaptations 

 that is one of the ways to which the healing art must turn in or- 

 der to enlarge its scope. 



Since we know that already developed pathological processes 

 can be only imperfectly or not at all affected by art, it should be 

 our more inflexible purpose to guard against their beginning, to 

 recognize the causes of disease, and render them harmless. But 

 this purpose must be comprehended in its widest sense ; it should 

 not be confined to the prevention of infectious diseases alone, or to 

 mere measures of sanitary policy, but should also include specific 

 means of cure. Thus, the treatment of malarious disease with qui- 

 nine is to all appearance etiological. The changes that have already 

 taken place in the blood-cells and the spleen are not reversed by 

 quinine, but the plasmodia of malaria are in some way destroyed, 

 and then the disease may be cured. 



The hope is not unjustified that in a nearer or further future 

 we shall learn to nullify by specific means the promoters of dis- 

 ease in many other infections. After nullifying the irritating 

 causes, the processes of Nature may be relied upon to complete the 

 cure. It is possible that this advance will be perfected incident- 

 ally, as has happened with quinine and malarious disease, and 

 with salicylic acid and rheumatism. There is also good ground 

 here for the hope that methodical research will be rich in re- 

 sults. The fruitful investigations of numerous contemporary 

 laborers permit much to be expected. And though the conflict of 

 opinions sways hither and thither, and although the knowledge 

 that has been gained relates only to diseases of animals, there is 

 no vital reason for supposing that the same results will not also 

 be reached for man. 



The efforts of the present are turned in three directions: to 

 cure bacterial diseases that have already become clinically visi- 

 ble ; to make infections harmless while in their incubatory stages ; 

 and especially to ward off infection. The last-named object is 

 the farthest-reaching one. It can be attained in two ways: by 

 sanitary protective measures against epidemics, and by confer- 

 ring immunity on the individual organism, of which vaccination 

 for small-pox is a typical example. Securing artificial immunity 

 by inoculation, and its scientific basis, are now in the full flow 



