proved an ignis f at u us instead ot&pharos to some of his 



followers. 



I have said that our air is full of the germs of ferments 

 dinVring from tin* alcoholic leaven, and sometimes seriously 

 interfering with the hitter. They arc tin- f this 



irdeii which often overshadow and choke t In- 

 ns take an illustrative cane. K \pose milk to 



:. It will, after a time, turn sour, separating like 

 blood into clot and serum. Place a drop of this sour milk 

 under a powerful microscope and watch it closely. You 

 see the minute butter-globules animated by that curious 

 quivering motion called the Brownian motion. But let 

 not this attract your attention too much, for it is another 

 motion that we have now to seek. Here and there you ol 



.ter disturbance than ordinary among the globules; 

 keep your eye upon the place of tumult, and you will 

 probably see emerging from it a long eel-like organism, 

 tossing the globules aside and wriggling more or less 

 rapidly across the field of the microscope. Familiar with 

 one sample of this organism, which from its motions receives 

 the name of vibrio, you soon detect numbers of them. It 

 is these organisms, and other analogous though apparently 

 motionless ones, which by decomposing the milk render it 

 sour and putrid. They are the lactic and putrid fen: 

 as the yea-t-j.lant is the alcoholic ferment of sugar. Keep 



and their germs out of your milk and it will continue 



. But milk may become putrid without becoming 

 sour. Kxamine such putrid milk microscopicallv, and yon 

 find it swarming with shorter organisms, sometimes asso- 

 ciated with the vibrios, sometimes alone, and often rnani- 

 iv.-ting a wonderful alacrity of motion. Keep the.-e 

 organisms and their ^erms out of your milk and it will 

 never puhvfv. Kxpose a Button-chop to the air and keep 

 it nmi-t: in summer weather it soon stinks. Place a drop 

 of the juice of the fetid chop under a powrful m 

 it is seen swarming with organisms resembling those in 

 the putrid milk. These or u r ani<ms. which receive the 

 common name of //,-/rm.* are the agents of all pntre- 

 K ep them and their m \oiir meat and 



oiyanism -..!, ii.iiin.: grave Hpecific differenoea are 



i.T till- .-,,111111. >ll IIHIIM- 



