VITALITY OF PUTKEFACTIVE ORGANISMS. 153 



boiled for fifteen minutes before introduction and for 

 five minutes afterwards. Tliese ditferences in the mode 

 and period of boiling were adopted to ascertain whether 

 they had any influence on the subsequent development 

 of life. In the case of the neutralized chambers, the 

 infusion for the three back tubes was boiled for fifteen 

 minutes outside before neutralization, and five minutes 

 in the chamber after neutralization. The infusion for 

 tbe'three front tubes was boiled fifteen minutes outside 

 after neutralization, and five minutes afterwards in the 

 chamber. If the potash used for neutralization carried 

 germs into the infusion, the difference between five and 

 twenty minutes in the period of boiling might, it was 

 thought, declare itself in the subsequent phenomena. 



Four days after its introduction the old Heathfield 

 acid infusion was found turbid throughout anfl covered 

 with scum. The scum and turbidity were sensibly the 

 same in all the tubes, though the period of boiling 

 varied from five to twenty minutes. On the same day 

 the neutralized infusion of the same hay was perfectly 

 brilliant and free from scum. Three days subsequently, 

 however (that is to say, on the 10th of November), 

 the neutralized tubes also became turbid and covered 

 with scum. 



The salient fact here to be noted is, that in neither 

 the neutral nor the acid chamber did a single tube of 

 the old Heathfield hay-infusion maintain its primitive 

 clearness and freedom from scum. 



The old London hay behaved substantially as the 

 old Heathfield hay, no single tube escaping either in the 

 neutralized or the unneutralized chamber. 



The dried new London hay comes next. A week 

 after its introduction every one of the six tubes con- 

 taining the acid infusion was turbid and coated with 

 scum. In the neutralized chamber, on the contrary, 



