Having thus satisfied ourselves as to the truth of the conclusion that _Bacteria_ are killed when the fluid containing them is boiled (at 212° F.), we are in a position to proceed with the inquiry as to the evidence which exists in respect to the statements made by M. Pasteur, Professor Huxley, and others, that fermentable fluids which have been boiled, will not undergo fermentation, either in vessels whose necks have been many times bent, or in those into whose necks a plug of cotton-wool has been inserted during the ebullition of their contained fluid. Organisms are not found in such cases, they say, because the “germs” from which the low organisms of infusions are usually produced, are arrested either in the flexures of the tube or in the cotton-wool. As I have before stated, however, it is obvious that if this explanation be the correct one, the preservation should be equally well marked in all cases--quite irrespectively of the amount of albumenoid or other nitrogenous material which may be contained in the fluid. Any exceptions to the rule should at once suggest doubts as to the validity of the explanation. It was shown[43] in 1865 by M. Victor Meunier that some fluids were preserved after having been boiled in a vessel of this kind, whilst others, submitted to the same treatment, speedily became turbid from the presence of _Bacteria_ and other organisms.[44] By these experiments he ascertained that strong infusions did frequently change, whilst weak ones might be preserved; and that even a strong infusion might be prevented from undergoing change if the period of ebullition were sufficiently prolonged. [43] ‘Compt. Rend.,’ t. lxi. p. 1060. [44] When boiled solutions, containing mannite, with a little nitrate and phosphate of ammonia, were employed, they always remained sterile. Similar negative results followed the employment of ox-gall. Of three decoctions of beef with which M. Meunier experimented, the two stronger of them were found to contain swarms of _Bacteria_ in about twelve days. Of three other flasks containing boiled urine, two also proved fertile. The fluids most frequently employed by M. Pasteur were yeast-water, the same sweetened by sugar, urine, infusion of beetroot, and infusion of pear.