VITALITY OF PUTEEFACTIVE OKGANISMS. 183 



was purely a difference of time. Inoculation with the 

 finished organisms acted more rapidly than infection 

 with the dust, but the effects were the same in the end. 

 On the 27th of January also nine melon-bulbs were 

 treated exactly like the turnip, being furnished with 

 sprigs of old Colchester hay, plugged with cotton-wool, 

 and hermetically sealed above the plugs. Six of them 

 were boiled for 215 minutes, and three for 220 minutes. 

 They were one and all permanently sterilized ; but, like 

 the turnip, all of them were open to infection by fresh 

 hay, dry dust, or living Bacteria, The specific gravity 

 of the melon-infusion was 1008. 



§ 17. Further Experiments on the Resistance-limit 

 of Germs to the Boiling Temperature, 



The amount of boiling which turnip-infusion failed 

 to withstand is shown by some of the foregoing experi- 

 ments; but to determine the limit of its resistance we 

 must begin with shorter periods. On the 1st of March, 

 therefore, eight groups of pipette-bulbs were charged 

 with turnip-infusion which had been prepared in an 

 atmosphere purposely infected with the germs of old 

 Heathfield hay. In every case, moreover, a sprig of the 

 same hay was placed in the air above the infusion. 

 The bulbs had their necks plugged with cotton-wool, 

 and were hermetically sealed above the plug. In this 

 condition the respective groups were boiled for the fol- 

 lowing times : — 



1st group 16 minutes. 



2nd „ 30 „ 



3rd „ 45 „ 



4tli „ 60 „ 



6tli „ 75 „ 



6tli „ 90 „ 



7th „ 105 



8th „ . . . . . 120 „ 



