and dandelions. The gentleman who introduced, from patriotic 

 motives, the Scotch thistle into Australia, has verified the truth 

 of the latter hypothesis, if it needed verifying. Xow disease 

 spreads in the same way. There are constitutions, and conditions 

 of the constitution, on which the seeds of disease fall innocuous. 

 There are conditions, on the other hand, in which the seed faUs 

 into good soil and bears fruit, some thirty, some sixty, some a 

 hundred-fold. The germs of epidemic disease seem usually to find 

 a suitable pabulum in water and damp earth, and the cholera 

 epidemic of which I have spoken above is an evidence of the 

 spread of a plague when it has found a suitable breeding-ground. 

 Hitherto the germs of disease have, to a great extent, eliided 

 the research of the enquirers in this field. But the practice of 

 vaccination and inociilation resting on this theory, enables us 

 to pronounce it absolutely true. 



I have been directed by our indefatigalile Secretary to certain 

 papers by Pasteur and others, in which the theory of these 

 disease germs is carefully worked out. Many of you may have 

 seen, however, a paragraph in the papers lately, as to the recent 

 outbreak of yellow fever in Rio. " In reporting the disastrous 

 outbreak of yellow fever in Rio this summer, Mr. Corbett, British 

 Minister in Brazil, draws attention to the remarkable residts of 

 the researches into the causes of infection, made by Dr. Freire, 

 one of the Medical Commission appointed by the Government 

 with that object. Having gathered from a foot below the surface 

 of the soil in the cemetery, some earth from the grave of a person 

 who had died about a year previously from this terrible disease, 

 Dr. Freire subjected it to an examination under a microscope, 

 magnifying 740 diameters, and discovered myriads of living 

 microbii, mostly identical with those found in the vomitings, 

 the blood, and other organic liquids of persons who have died 

 of the fever." 



The observations, which are set forth in detail, together 

 with other interesting experiments in the report which Mr. Corbett 

 forwards, are verified by three other medical men. They show, 

 according to Dr. Freire, that " the germs of yeUow fever perpetuate 

 themselves in cemeteries, which are like so many nurseries for 



