PUTKEF ACTION AND INFECTION. 59 



larger and more languid, but not at all so numerous as 

 in the watered tube. On the 5th of October some of 

 the exposed tubes began to clear ; as if the Bacteria 

 had died through lack of nutriment, and were falling 

 as a thick sediment to the bottom. 



During these changes the ^protected tubes t<;ere 

 visibly unaltered, the liquid tuithin every one of them 

 remaining as clear as it had been on the day of its 

 introduction. 



In this instance I was specially anxious to verify the 

 result by repetition. Two other cases were therefore 

 fitted up to contain three tubes each, and instead of a 

 door a movable panel was placed at the back. After 

 two or three days' rest both cases were found free from 

 floating matter, and on the 1 st of October the turnip- 

 infusion was introduced, and boiled for five minutes in 

 a bath of brine. 



In the former experiment the temperature of di- 

 gestion was maintained by keeping the beaker contain- 

 ing the turnip in a bath of warm water. In the present 

 instance the turnip was sliced in a dish and placed 

 before a fire. An occult but efficient power like that 

 already ascribed to the actinic rays', might, I thought, 

 be ascribed to radiant heat, and I therefore copied to 

 the letter the mode of digesting pursued by modern 

 heterogenists. 



Adjacent to the closed cases was placed a series of 

 three exposed tubes, containing a liquid prepared in 

 precisely the same way. On the 4th of October the 

 exposed tubes were all turbid, and swarmed with Bacteria. 

 In two of the tubes they were distinctly more numerous 

 and lively than in the third. Such differences between 

 sensibly conterminous tubes, containing the same infu- 

 sion, are frequent. On the 9th, moreover, the two most 

 ' 'Nature,' vol. iii. p. 247. 



