Bacteria in Organic Infusions. 125 



so by Dr. Ferdinand Cohn in experiments made with peas and 

 infusion of peas.* Further, we had Hmited the bulk of our infu- 

 sions and the size of our experimental tubes, in view of the obvious 

 consideration that the larger the mass and area to be guarded 

 against contamination the greater the chance of failure in that 

 respect. Thirdly, it had not occurred to us to make use of vessels 

 in these experiments of a form so inconvenient and difficult to 

 thoroughly guard against effects of '' spluttering," and to thoroughly 

 heat by boiling, as the retort. Nor could we guess, in the absence 

 of any directions on that point from Dr. Bastian, that it was desir- 

 able to exclude the rind of the turnip from the preparation of the 

 infusion. The correspondence in ' Nature/ however, indicated that 

 " pounded " cheese (necessarily in a condition of sohd lumps) was 

 added (in some cases) to his experimental vessels after the turnip- 

 infusion, and was present during ebullition. It also appeared that 

 retorts capable of holding two ounces were the vessels used ; whilst, 

 on grounds not given, it was considered advantageous by Dr. Bastian 

 to peel the turnips before slicing them. 



The following experiments were accordingly made : — 



An infusion of turnip (minus the rind) was prepared and filtered ; 

 it had sp. gr. 1012-7. In the experiments Nos. 34 to 47 two- 

 ounce retorts were used, and the bulb half filled with the experi- 

 mental infusion. 



No. 34. The infusion neutralized with KHO, About two grains 

 of pounded cheese in pellets added to the retort. 



Nos. 35, 36. Infusion not neutralized. About two grains of 

 pounded cheese in pellets added to the retort. 



Nos. 37, 38, 39. The simple infusion. 



No. 40. The simple infusion, to which were added a few drops 

 of an emulsion of cheese prepared with some of the turnip-infusion 

 and new cheese, the emulsion having been filtered. 



No. 41. The simjjle infusion. 



Nos. 34 to 40 were boiled for five minutes ; they were then 

 preserved in the air-bath at a temperature of 35° C, and sealed 

 approximately during ebuUition. Four of them, including No. 36, 

 were subjected to a further boiling of fifteen minutes in a water- 

 bath after sealing. 



No. 41 was boiled for five minutes and placed on a shelf with 

 its mouth open. 



Subsequent appearances in Betorts Nos. 34-41. 



On Feb. 15th Nos. 34, 35, 37 were opened and found to be 

 perfectly sweet and free from a development of Bacteria or other 

 organisms. 



* ' Beitrage zur Biologie der Pflanzen,' Brcslau, 1872. 



