PUTREFACTION AND INFECTION. 51 



through a stufhng-box of sticky cotton-wool. The width 

 of the aperture closed by the india-rubber secures the 

 free lateral play of the lower end of the pipette. Into 

 two other smaller apertures in the top of the chamber 

 are inserted, air-tight, the open ends of two narrow 

 tubes, intended to connect the interior space with the 

 atmosphere. The tubes are bent several times up and 

 down, so as to intercept and retain the particles carried 

 by ouch feeble currents as changes of temperature might 

 cause to set in between the outer and the inner air. 



The bottom of the box is pierced with two rows of 

 holes, six in a row. in which are fixed, air-tight, twelve 

 test-tubes, intended to contain the liquid to be exposed 

 to the action of the moteless air. 



The arrangement is represented in fig. 2, where w w 

 are the side windows through which the searching beam 

 passes from the lamp I across the case c ; p is the pi- 

 pette, and a, 6, are the bent tubes connecting the inner 

 and outer air. The test-tubes passing through the bot- 

 tom of the case are seen below. 



On the 10th of September, 1875, this case was closed. 

 The passage of a concentrated beam across it through 

 its two side windows then showed the air within it to be 

 laden with floating matter. On the 13th it was again 

 examined. Before the beam entered, and after it quit- 

 ted the case, its track was vivid in the air, but within 

 the case it vanished. Three days of quiet had sufficed 

 to cause all the floating matter to be deposited on the 

 interior surfaces, where it was retained by a coating of 

 glycerine, with which these surfaces had been purposely 

 varnished. 



§ 3. Dep07'tment of Urine. 



The pipette being dipped into the tubes, fresh urine 

 was poured into eight of them in succession on the 1 3th 



