1876.] Phenomena of Putrefaction and Infection. 181 



On 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 row 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 whole tray of one hundred tubes, 

 twenty-seven were either muddy or cloudy on the 11th. Thus, doubt- 

 less, in a contagious atmosphere, are individuals successivly 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 few, 

 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 vigour. These differences are to be referred to differences in 

 the germinal matter, for the same infusion was presented everywhere to 

 the air. Here also we have a picture of what occurs during an epidemic, 

 the difference in number and energy of the Bacterial swarms resembling 

 the varying intensity of the 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 susceptibility 

 as two samples of one and the same mutton-infusion. Experiments with 

 other trays are described in the paper, and calculations are made regard- 

 ing the number of germs held in suspension by the air. 



The author traces still further the parallehsm of these actions with 

 the progress of infectious disease. The ' Times ' of January 17 con- 

 tained a letter on typhoid fever, signed " M.D.," in which occurred 

 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 Corporation return for 1874, no less than 

 14,319 houses or dwellings — many under one roof, on the ' flat ' system 

 — in which there are no house connexions 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 in 

 pails or pans, and remains in their midst, generally in a partitioned-off 

 corner of the living-room, until the next day, when it is taken down to 

 the streets and emptied into the Corporation carts. Drunken and 

 vicious though the population be, herded together like sheep, and with 

 the filth collected and kept for 24 hours in their very midst, it is a 

 remarkable fact that typhoid fever and diphtheria are simply unknown 

 in these wretched hovels." 



This case has its analogue in the following experiment, which is re- 



ganze Tage vollig reinen Luftverhaltnisse wechseln." (Ehrenberg, " Infusionsthier- 

 chen," 1838, p. 525.) The coincidence of phraseology is surprising, for I knew 

 nothing of Ehrenberg's conception. My " clouds," however, are but small miniatures 

 of his. 



