464 ILLINOIS STATE ACADEMY OF SCIENCE 



test that is almost infallible. It consists in injecting 

 into the skin of the arm or any where a few drops of a 

 high dilution of diphtheritic toxin. If in 3 or 4 days a 

 small area of redness develops which gradually disap- 

 pears, leaving a discolored scaly spot, the child is sus- 

 ceptible. If nothing results from this intra cutaneous 

 injection, the child is naturally immune and probably for 

 life. I have given nearly 8000 of these tests. It is al- 

 most painless and absolutely devoid of any danger what- 

 ever. Having determined by the Schick test that about 

 one-half of the school children might get diphtheria if 

 exposed to it, no vivid imagination is required to under- 

 stand the desirability of immunizing, if possible, those 

 that are susceptible. To me, how a great discovery is 

 made is as interesting as the discovery itself. In this 

 instance, as often happens, chance is entitled to almost as 

 much credit as science in elaborating this most wonder- 

 ful discovery. Again and again opportunity knocked at 

 the Laboratory door of science, and offered a way and 

 means of preventing this dreadful disease. As I shall 

 presently indicate, the solution of this problem of active 

 immunization in diphtheria was going on right under the 

 eyes of every antitoxin laboratory worker in Christen- 

 dom long before they knew it. I have thought some- 

 times that research workers, elated with their victory 

 over laboratory diphtheria, have been slow to realize 

 the importance of discovering some way of permanently 

 immunizing the oncoming hoards of susceptible children. 

 Behring himself sooner or later saw the necessity of ac- 

 tive immunization because the protection afforded by 

 immunizing doses of antitoxin was short lived. This 

 often necessitated repeated doses of antitoxin which 

 sometimes resulted in serious anaphylactic reaction. It 

 is 14 years since Smith suggested, but 9 years since Beh- 

 ring, Park and others first used TA mixtures to actively 

 immunize children. Of course this time is too short for 

 us to be dogmatic, but the results thus far attained jus- 

 tify us in as'king for the widest possible use of such mix- 

 tures if we are to limit further the ravages of this disease. 

 Time will, I believe, demonstrate that few discoveries in 

 medical science have been made which otfer greater po- 



