24 Cincinnati Society of Natural History. 



microbe. We have before us a talile of the mortality from 

 pneumonia in Cincinnati for ten years, from i8Si to 1890, 

 inclusive, compiled from Cincinnati Board of Health reports. 

 For Deceml)er, January, February and March we have 2,316 

 deaths. For June, July, Augu.st and vSeptember S23, not much 

 more than one-third of the number. The year 1884 had an 

 immense rainfall, as we all know, and was followed in January 

 and February, 1885, by a great increase in death rate from 

 pneumonia, namely, 123 in January and 104 in February. 

 These statistics can be paralleled by those from many different 

 sources and countries. 



These figures, with reference to sea.sonal prevalence, do not 

 exclude the bacterial influence. But they at least sustain the 

 idea of the depressing effect of cold upon the system, and at 

 least some agencj' in impairing its power of resistance. 



We have all become sufficiently fiimiliar with the complica- 

 tions of our influenza epidemic, now ])ast, to know that pneu- 

 monia and its microbe and its toxic element have obtruded 

 their dangerous interference, and that without any question 

 of cold as a cause. The microbe of the influenza, by its 

 virus, depresses the system and opens the way for the pneu- 

 monia virus. vSuch cases become what physicians know as 

 "Mixed Infection," and are, therefore, the more dangerous. 



Phthisis pulmonalis or consumption has, by Koch's discov- 

 ery, l)een eliminaLed from the list of diseases caused by cold. 

 It is generally believed now to rank as a microbic disease. 

 Koch's proposed cure was worked out on the ]:>lan of an 

 attenuation of the virus peculiar to the bacilli tuberculosis. 

 It is a solace for a consumptive patient to feel that the aggra- 

 vations of his disea.se are traceable to a cold, but his physician 

 interprets them as the evidences of progress in the destruc- 

 tive work of the microbe and its virus. 



Most of human infectious diseases have their greatest 

 development during the cold months. Tonsillitis, diphtheria, 

 crouj), scarlet fever, etc., prevail mostly in Winter, but they 

 show such sjiecific differences and such infection.^" j^hases as 

 not to be explained by a single cause, like llial of coUl or heat. 



Instances of this comjilex relationship between external 

 conditions and internal liredisjionents and diseases are found 

 during the hot months of the \ear. IvxpLriment has shown 



