The Pioche weekly record. [volume] (Pioche, Nev.) 1877-1900, 1890-06-07
MODERN BACTERlOLOGY.


That Peo2issths sss.y'a.ansA'
Our knowledge in no department of
science has made greater strides during
the last few years than in that of bac-
teriology. The existence of organisms
far smaller than any thing that the
naked eye can discern was, says Cham
bers' Journal, fact little suspected
until comparatively recent times; and
ever since the microscope first revealed
to our eyes the world of ''the infinitely
little" as it has been felicitously
called, our knowledge of these microscop-
ic forms of life has gone on increasing.
These micro-organisms exist in the
atmosphere and in water: but it is only
within the last few years that we have
had any means of arriving at an approx
innate idea of the extent to which they
are present in these media 1t is in the
first instance to the brilliant inyestiga-
tlons OF M. Pasteur that we owe our
knowledge on this point; and the i'm
portant experiments he was the first to
carry out have been developed
and extended by others. Prof. Tyn-
dali has shown that in calm air
rapid subsistence of these microbes takes
place. The distinguished German
psychologist, DR.. Koch, has devised a
method by means of which we are
enabled to form an estimate of the num-
Der or these heterogeneous present in
hmeasured quantity of either water or
ar. The method consists in cultivating
the germs in solid medium (gelatine
Is most commonly used). Each organism
thus grows and multiplies on the spot
where it is planted, as it is prevented
from moving. The progeny of each
mlcro-organism in this way gather
round the parental home, and we have
lpthe course of short time, instead OF
the single organism, large colony.
Some interesting experiments were
illaoe on this point short time ago by
Dr. +. f. Frankland. The air was tested
at different places and under different
circumstances. 1t was found that the
number OF organisms present in the at
mosphere differed at different seasons of
the year, the largest proportion being
Iound during the summer months. Ina
certain volume of air 1.-TWO gallons) col
lected on the top of the Science and Art
department. buildings at South Ken
2pgton, one hundred and i've of these
r1.cso-organisms were found to be pres
ent. This was in the month of August.
INDOORS, OF course, the number is yerv
much greater. Thus, in a similar ouan-
tlty OF air collected at the rooms of the
Royal Society during Conversations.
no fewer than four hundred and thirtv-
Two were found to be present; while an
other experiment showed that from the
air OF third-class railway carriage con-
tanning ten people no fewer than three
thousand one hundred and twenty mi
o1obes fell per minute on square foot.
SO much for the living organisms in
our atmosphere; now for word or two
On Inc dead inorganic particles in the
ar These are infinitely more numer-
GUS than the living germs; and an ex-
Hemely ingenious method has recently
peen devised by Mr.. John Aitken.
=. :, ~ ). e., for the purpose of estimating
~ snoir number. Like the organic germs,
aoy are Infinitely minute in size, most
~ 'lem being altogether undetected by
.ne most powerful microscope. 1t was
necessary, therefore, to have recourse
w W some method of making them visible.
he plan adopted was as follows. srhe
air 70 De tested was admitted into a
.a,se glass vessel, where it was satu-
l".eu with water-vapor; then supersatu-
is'eo by slightly expanding it by means
" an air-pump. The result was a fog:
ana as it is known that a fog is caused
w those dust-particles becoming sur.
ouiueu py watery envelope, the nam-
psf oi 1og-particles shows the number
y. VI "ust-particles. The counting of |
.nese 1og-particles was effected in the
showing ~ way: A very small portion of
,ne ar TO be tested was mixed with a
."ige quantity of air which had been
- absolutely pure by filtering it
through cottonwood. The mixture was
10; In aomitted into a large glass re-
reiser and saturated as above described.
ns The dust-particles were so few. in
Eau OF a fog small miniature rain
"as formed, and the number of these
su.ail ralndrops falling on small silver
n,ftor was counted, and, by simple
sioulatlon, the amount in the quantity
= ar originally admitted thus esti-
naoea. fh. The following are some results
'DIained: :, 1t was found that the air out
,aoe uurlng rain contained per cubic
:. a.n o2l,OOO dust-particles; that during
"Af weather the number present was