178 THE FLOATING-MATTER OF THE AIR. 



being permitted to enter our laboratory. The cucumber 

 used for the infusion was also kept clear of the infected 

 air ; it was sliced and digested in the shed, the infusion 

 was there filtered, introduced into the tin chambers, and 

 boiled subsequently for five minutes. 



The result was not that expected. Not a single 

 tube of either of these two chambers escaped con- 

 tamination. They one and all behaved like the 

 same infusion in the infected laboratory, becoming 

 in three days turbid throughout and laden with fatty 

 scum. 



I have been daily and hourly impressed with the 

 parallelism between these phenomena of putrefaction 

 and those of infectious disease. A further illustration 

 of this parallelism is here presented to xis. The clothes 

 of my assistants who prepared the infusion in the shed 

 had been worn in the laboratory, a transfer of infection 

 by one of the modes of transport known to every 

 physician being the result. The thoughtful physician 

 cannot indeed fail to see the absolute identity of deport- 

 ment between the contagia with which he is familiar, 

 and those assailants of my infusions against which I 

 have been contending so long. 



With regard to the shed my first step, after this 

 preliminary failure, was to disinfect it. This was done 

 by washing every part of it, first with a mixture of 

 carbolic acid and water, and secondly with a solution of 

 caustic potash. "When the whole was well dried, new 

 tin chambers furnished with new tubes were introduced. 

 Cucumbers and beef fresh from the market were also 

 digested in the shed, my assistant taking care to cover 

 his legs with clean linen trowsers, and his body with a 

 new blouse. There was one chamber devoted to the 

 cucumber and another to the beef. Into the former 

 the infusion was introduced on the 1 9th, and into the 



