PUTKEFACTION AND INFECTION. 67 



It was introduced into a case containing three protected 

 tubes, and boiled there for five minutes in the brine- 

 bath. Hung on to the chamber at the same time were 

 three tubes containing the same infusion, but exposed to 

 the common air. On the 1 3th Bacteria were numerous 

 in the exposed tubes, and soon afterwards all three of 

 them became thickly muddy and putrescent. They 

 •continued so for months. 



The protected tubes, on the contrary, showed 

 throughout a bright yellow liquid, as transparent 

 and fresh as it ivas on the day of its introduction 

 into the case. 



■§ 11. Infusions of Hare, Rabbit, Pheasant, and 

 Grouse. 



For the sake of economy, as so many of them were 

 employed, the shape of the cases was subsequently varied. 

 The rounded end of a tall glass shade was cut off, so as 

 to convert the shade into a hollow cylinder, open at 

 both ends. This was set upright on a wooden stand, 

 and cemented to it air-tight. Through the stand passed 

 three large test-tubes also air-tight. To the top of 

 the cylinder was cemented a circular piece of wood, the 

 middle of which was occupied by a pipette passing first 

 through india-rubber and then through a stuffing-box 

 of cotton-wool moistened by glycerine.^ The air within 

 the case was connected with the air without by means 

 of the open bent tubes already described. 



In the first experiments made with these cases defects 

 of construction were revealed during the boiling of the 

 infusions. But increased experience enabled me to 



^ In the earlier experiments the india-rubber formed the bottom 

 of the stuffing-box, where particles were sometimes detached from 

 it by the motion of the pipette. To prevent this the positions of 

 wool and rubber were afterwards reversed. 



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