IMMUNOLOGY 19 



described by the physicians of the medieval ages; our pneumonia 

 death-rate is still what it was when the earliest records on the subject 

 were kept, and is virtually the same for the millionaire in his marble 

 palace, surrounded by doctors and nurses, as for the tramp who is 

 cared for by the roadside by his brother tramps. The "virulence" of 

 an epidemic of scarlatina or measles may vary, but our death-rate in 

 the long run is virtually the same. Where actual progress has been 

 made in the treatment of disease, such progress has been due not to 

 our therapeutic interference by means of drugs, but to a recognition, 

 be it ever so slight, of those factors by w r hich nature herself, unaided 

 and at the same time unhampered by empirical drug treatment, seeks 

 to accomplish that end. For after all the very thing which physicians 

 have sought to accomplish in all the centuries that have passed, viz., 

 the cure of disease, that very thing nature has accomplished by 

 herself, before our very eyes, countless millions of times. 



Nature herself cures 75 per cent, of the pneumonia cases, while 

 the physician fails to cure any, for surely he cannot claim as his own 

 what nature does, and he evidently loses the 25 per cent, that nature 

 loses. The fact that nature does not cure all cases could of course 

 be interpreted as indicating that the means at nature's command 

 are after all not perfect. That is naturally a debatable point. So 

 much, however, seems certain that nature's ways, so far as we have 

 become familiar with them, are the only specific ways along which 

 progress seems possible, and that drug treatment, if it ever shall 

 become of value, must start from a different basis, and that basis 

 must be a knowledge of the principles which underlie the interaction 

 between the disease-producing agent and the affected organism. 



Immunology. The study of these forces constitutes the domain of 

 immunology, of which in turn modern chemotherapy, serum therapy, 

 and vaccine therapy are the logical products. The earliest work in 

 this direction is intimately linked with the name of Pasteur, and 

 constitutes the basis of all future w r ork. It was Pasteur who first 

 demonstrated that material progress in the treatment and prevention 

 of the so-called infectious diseases could only be achieved by the 

 recognition of the fact that the production of active resistance to 

 an infecting agent on the part of a susceptible animal necessitates 

 the introduction of the infecting agent into the animal body; in 

 other words, that acquired immunity, be this absolute or relative, 

 temporary or permanent, is merely a phase of infection. The study 



