THE 



POPULAR SCIENCE 



MONTHLY. 



JULY, 1914 

 MAN AKD THE MICKOBE 



By Pbofessob C.-B. A. WINSLOW 



THE AMEBICAN MUSEUM OF NATUBAE HISTOBY, NEW YOBK 



A CASE of measles or typhoid fever is not only a most unpleasant 

 kind of practical problem, but a natural history phenomenon of 

 a mysterious and interesting sort. Here is a person who wakes up ap- 

 parently well and goes about his daily tasks as usual. Gradually he is 

 conscious of some strange clog in the machine, a dragging of the wheels, 

 such as we experience when a carriage passes from a good road into a 

 sandy by-way. Pains and aches begin to be felt in head and back. The 

 general weakness increases, and, with or without a sharp chill, the pa- 

 tient gives up and takes to bed. Fever has set in. The vigorous and 

 active human animal of the morning has been changed in a few hours to 

 a mere wreck of his former self. What has happened? What subtle 

 force has produced so sudden and mysterious a catastrophe? 



The later history of such an attack is almost as remarkable as its in- 

 ception. Most diseases go on and grow worse unless something definite 

 is done to remove their exciting cause. If, however, your measles or 

 typhoid patient be let alone, or only protected by hygienic precautions 

 against certain secondary results, 99 times out of 100 in the case of 

 measles, and 9 times out of 10 in the case of typhoid fever, he will get 

 well. These are " self-limited " diseases, to use the old expressive term. 

 They run a course of so many days or weeks, and then, unless death or 

 some complication supervenes, there is a steady progressive recovery. 

 The temperature falls, the mind clears, the strength returns, the patient 

 is as he was before, with one important exception, that he is now, to a 

 greater or less extent, and for a longer or shorter time, resistant or 

 immune against the particular malady from which he has suffered. 

 Think what a curious phenomenon this really is, divested of the cloak of 

 familiarity with which it is commonly invested. What sort of strange 

 process goes on in the body, which has a definite cycle like the life of an 

 animal, fulfils its appointed round, and then draws to a close, leaving 

 only the impress of immunity to mark its passage. 



