GERM THEORY OF FERMENTATIVE CHANGES 317 
to the present time (September 1873), more than three months after it was 
prepared. 
The urine was not boiled at all, but was obtained altogether unaltered by 
a very simple process, depending upon what appears to be a fact of high interest 
both physiologically and pathologically, that a mucous canal in a state of health 
does not permit the growth of foreign organisms in its immediate vicinity, so 
that preliminary external application of a carbolic lotion (1 to 40) is sufficient 
to ensure an uncontaminated state of the fluid, which, with its unaltered mucus, 
is a much more favourable nidus for organic development than after boiling. 
One other piece of apparatus requires a short notice, viz. that used for 
withdrawing fluid from the experimental glasses for inoculation or examination. 
The most convenient means for this purpose I have found to be what may be 
called a ‘syringe pipette’, consisting of a small syringe with a piece of glass 
tube connected with it by a caoutchouc adapter, the junction being self-support- 
ing but yielding (as distinguished from rigid). This last property permits the 
use of a very delicate tube without risk of breakage when it touches the side 
of a glass; and it is of great importance that the tube should be of as thin glass 
as possible. It can then be heated fully when dry by once drawing it quickly 
through the flame of a Bunsen’s burner, and a few seconds suffice for its cooling. 
The tube, which is about a line in diameter, is drawn out a little at the end, 
and is bent at an obtuse angle about two inches from the syringe ; so that the 
latter is not held over the liquid during the process. Care is taken not to drive 
any air from the syringe into the tube after heating the latter, and rather more 
of the liquid than would suffice for inoculation is taken up, so that the part left 
in the tube may protect that which is ejected from air from the syringe. 
To the general reader these details may seem almost unpardonably minute, 
but for any one who is desirous to repeat similar experiments I venture to hope 
they will not be found so. 
On the 14th of June I drew off for the first time some milk from the flask 
which was exhibited to the Royal Society of Edinburgh in April as having its 
contents still fluid, and therefore probably unaltered, though prepared seven weeks 
previously, and under difficulties as compared with the material of later experi- 
ments, inasmuch as it was boiled by the direct flame of the lamp, the extreme 
inconvenience occasioned by the frothing of this flask having led to the sug- 
gestion of the boiling-water bath above described. Also the cotton-wool over 
the mouth was not carbolized, a piece of muslin between the cotton and the 
flask being alone treated with the ethereal solution of the acid. Nevertheless, 
the cotton filter had proved efficient in spite of the often repeated rapid rushing 
of air into the flask which must, of course, have occurred whenever the lamp 
