VITALITY OF PUTEEFACTIVE OEGANISMS. 231 



shown the slightest sign of yielding. The liquid within 

 all of them is as brilliant as it was when first intro- 

 duced. 



In every case here mentioned the liquid, after boil- 

 ing, was exposed for several days to a temperature of 

 50° C. 



The conflict described in the foregoing pages and 

 the search for principles to reconcile the results occupied 

 me too long to permit of my doing more than break 

 ground on the subject of urine. I entertain, however, a 

 strong opinion that by a little practice with this liquid, 

 its sterilization by five minutes' boiling might be ren- 

 dered certain in every case. As the experiments stand, 

 they sufficiently negative the conclusion that neutralized 

 urine furnishes a specially convincing illustration of 

 spontaneous generation. 



§ 28. Hermetically-sealed Flasks exposed to the Sun 

 of the Alps. 



A remark of Dr. Bastian's, wherein he refers to the 

 power of the actinic rays of the sun to promote spon- 

 taneous generation,* caused me to take with me to 

 Switzerland a number of flasks hermetically sealed with 

 special care and charged with infusions of various kinds. 

 Eighty of them were carefully packed in sawdust in 

 London ; but on my arrival at the Bel Alp, which 

 stands at an elevation of some 7,000 feet above the 

 sea, I found only forty-five of them unbroken. They 

 were thus distributed : — 



Beef 12 flasks. 



Mackerel 12 „ 



Turnip 12 „ 



Fowl 9 „ 



• ' Nature,' vol. iii. p. 247. 



