APPENDIX. 323 



and from life. They embraced specimens of all tlie sub- 

 stances above mentioned and some others. 



Briefly expressed, then, the evidence furnished by six 

 months' assiduous work during the autumn, winter, and 

 spring of 1875-76, proved conclusively that in the 

 atmospheric conditions then existing in the laboratory of 

 the Royal Institution, not one of the many hundred flasks 

 and tubes experimented on failed to be sterilized by five 

 minutes' boiling, and no countenance was given to the 

 notion that any of these once sterilized infusions possessed 

 the power of spontaneously generating life. 



The investigation embodied in the memoir now sub- 

 mitted to the Society was opened in the summer of 1876 

 by a series of tentative experiments on turnip-infusions, to 

 which were added varying quantities of bruised or pounded 

 cheese. Seven difierent kinds of cheese were employed, 

 fifty-seven test-tubes being charged with the mixture and 

 exposed to the self-purified air of closed chambers. 



The majority of these mixtures remained unchanged ; a 

 minority became charged with organisms, which are, in my 

 opinion, completely accounted for by reference to the 

 protective action of the cheese. In the memoir of which 

 this is an abstract such protective action is illustrated by 

 the fact that when ordinary mustard seeds were tied 

 together in a calico bag, they resisted the boiling tem- 

 perature for a considerable multiple of the time which 

 sufficed to kill them when no bag enveloped them. The 

 bag and outside seeds protected the interior ones. 



Not temperature alone, but the ability to diffuse its 

 juices or salts, is a condition of prime importance in the 

 destruction of the integrity and life of a germ by boiling 

 water. Without diffusion a germ may withstand tem- 

 peratures competent to utterly destroy it where diffusion is 

 free. I need not remark on the imperviousness of cheese 

 to water, and its consequent power to prevent diffusion. 



These summer experiments on turnip- cheese infusions 

 were, however, merely tentative, and I purpose completing 

 them hereafter. 



Y 2 



