% AND ITS BEARINGS ON PATHOLOGY 361 
panying it. When a sufficient quantity has been introduced, the tap is again 
turned off, and the syphon is withdrawn through the antiseptic rag, and a fresh 
cap of carbolized cotton is tied over the mouth of the flask when the rag is 
withdrawn. 
I have said that before I saw my mistake in using the funnel, I never 
succeeded with milk. Since I have adopted the syphon I have charged many 
flasks and never failed. Here is a flask of boiled milk (or rather of milk that 
has been exposed to a temperature of 210°) prepared on the 7th of August, and 
remaining we may safely say as pure as it was then. You observe it is still 
perfectly liquid and unaltered in appearance. Now I venture to remark that 
this failure and correction of the failure are extremely instructive, as showing 
how the development of organisms under circumstances in which we cannot 
at first explain their occurrence may be really due to fault on our part, defect 
in our own manipulation. 
So much for our method of procedure. I will now go on with the main 
subject of this communication. I selected the lactic fermentation as one pecu- 
liarly favourable for investigation : first, because the effects which it produces 
in milk are extremely striking and readily recognized—the solidification which 
takes place being obvious at a glance, and the souring as shown by test paper 
being also a very conspicuous change; and in the second place because the 
ferment which occasions these alterations is, in ordinary localities, a very rare 
ferment ; and if it be rare, it is not likely that any defects in our manipulations 
will lead to its accidental introduction. 
It may seem strange that the ferment that leads to the souring of milk 
should be rare, but such is the fact ; in dairies it appears to be universal, but 
in the world at large it is scarce. If you charge a series of pure liqueur-glasses 
with boiled milk and take off their caps so as to expose them to the air for about 
half an hour each, doing this for the various glasses at different times of the 
day or in different rooms, you will be sure to have organisms develop in all 
of them, of the nature of filamentous fungi and bacteria; and you will see 
fermentative changes ensue; but, so far as my experience goes, you will not 
see the coagulation and souring of the lactic fermentation, nor will you find 
under the microscope the peculiar organism to which I have given the name of 
Bacterium lactis, which is represented here (Plate XIV, Fig. 9) as it occurs in 
ordinary curdled milk, and which may be seen under one of the microscopes on 
the table, in milk taken from the cow yesterday. 
This organism is a motionless bacterium, that is to say, exhibiting no move- 
ment except a slight jogging, occurring most commonly in pairs, but frequently 
in chains of three, four, or more individuals, each segment being of somewhat 
