Professor Tyndall on Germs. 



it by the interspace between two clouds. But 



mottled sky, the various portions of the landsca 



visited by shade, so, in the long run, are tl 



tray touched by the Bactei-ial clouds, the ] 



fection of them all being the consequence. 



these results with the experiments ■ ^ 



of the cause of so-called spontaneous generation, and with other 



Oil the 9th of November a second tray containing one hundred 

 tubes filled with an infusion of mutton was exposed to the air. 

 On the morning of the 11th six of the ten nearest the stove had 

 given way to putrefaction. Three of the rows most distant from 

 the stove had yielded, while here and there over the tray particular 

 tubes were singled out and smitten by the infection. Of the 

 wh(i]e tray of one hundred tubes, twenty-seven were either muddy 

 or cloudy on the 11th. Thus, doubtless, in a contagious atmos- 

 phere, are individuals successively struck down. On the 12th all 

 the tubes had given way, but the differences in their contents were 

 extraordinary. All of them contained Bacteria, some i'e\\, others 

 in swarms. In some tubes they were slow and sickly in their 

 motions, in some apparently dead, while in others they darted 

 about with rampant vigor. These differences are to be referred 

 to changes in the germinal matter, for the same infusion was 

 presented everywhere to the air. Here also we have a pictuie of 

 what occurs during an epidemic, the difference in number and 

 gy of the Bacterial swarms i-esembling the varying intensity 

 ^-^ disease. It becomes obvious from these experiments that 

 of two individuals of the same population, exposed to a contagious 

 atmosphere, the one may be severely, the other lightly attacked, 

 though the two individuals may be as identical as regards suscepti- 

 bility as two samples of one and the same mutton infusion. 



The author traces still further the parallelism of these actions 

 with the progress of infectious disease. The Times of January 

 nth contained a letter on Typhoid Fever signed "M.D.," in 

 which occurs the following remarkable statement : — " In one part 

 of it (Edinburgh), congregated together and inhabited by the 

 lowest of the population, there are, according to the Corpora- 

 tion return for 1874, no less than 14,319 houses or dwellings — 

 many under one roof, on the 'flat' system — in which there 

 are np house connections whatever with the street sewers, and, 

 consequently, no water-closets. To this day, therefore, all the 

 excrementitious and other refuse of the inhabitants is collected 

 the passage of a Bacterial 



two clouda. Certain"' capricea" in the behavior of dressed wounds may 

 >e accounted for in this way. Under the heading " Nothing new under 

 ' Prof. Huxley has just sent me the foUowmg remarkable extract :— 



energy 

 of the 



^^^, u^^ ueuBu gauz leere i.unuiiiB»cu. jd ganze Tage vollig reinen 



iiuftverhaltnisse wechaeln." (Ehrenberg, "Infusions Thierchen," 1838, p. 525.) 

 ^ne coincidence of phraseology is surprising, for I knew nothing of Ehrenberg 8 

 conception. My " clouds," however, are but smaU miniatures of his. 



