Walker Lake bulletin. (Hawthorne, Nev.) 1883-1926, 1890-08-27
MODERN BACTERioLoGY.
What Science Knows About the ssMotes
That People the Sunbeam"


What Science Knows About the 4"Motes
That People the Sunbeam"
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 tho 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
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 investiga-
tions of NJ. 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 a
rapid subsistence of these microbes takes
place. The distinguished German
physiologist, DR.. Koch, has devised
method by means of which we are
enabled to form an estimate of the num-
Der of these heterogeneous present in
a measured quantity of either water or
air. 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
micro-organism in this way gather
round the parental home, and we have
in the course Of short time, instead of
the single organism, large colony.
Some interesting experiments were
made on this point short time ago by
DIR. P. 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
found during the summer months. In
certain volume of air 1.-TWO gallons) col
lected on the top of the Science and Art
Department buildings at South Ken
sington, one hundred and five of these
micro-organisms were found to be pres
ent. This was in the month lof August.
Indoors, of course, the number is very
much greater Thus, in similar guam
tity of air collected at the rooms of the
Royal Society during conversazione,
no fewer than four hundred and thirty
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
crobes fell per minute on square foot
So much for the living organisms in
our atmosphere; now for word or two
on the dead inorganic particles in the
air. These are infinitely mere numer-
GUS than the living germs; and an ex-
tremely ingenious method has recently
been devised by Mr.. John Aitken,
It. r. S. E., for the purpose of estimating
their number. Like the organic germs
they are infinitely minute in size, most
of them being altogether undetected by
the most powerful microscope. 1t was
necessary, therefore, to have recourse
to some method of making them visible
The plan adopted was as follows: The
air to be tested was admitted into q
large glass vessel, where it was satu-
rated with water-vapor: then supersatu-
rated by slightly expanding it by means
of an air-pump. The result was fog;
and as it is known that fog is caused
by those dust-particles becoming sur
rounded by watery envelope, the num-
Der OF fog-particles shows the number
of Gslst-psrticles. The counting OF
these fog-particles was effected in the
following way: A very small portion of
the air to be tested was mixed with a
large quantity of air which had been
rendered absolutely pure by fltering it
through cottonwood. The mixture was
then admitted into q large glass re-
ceiver and saturated as above described.
AS the dust-particles were so few, in
stead of fog small miniature rain
was formed, and the number of these
small raindrops falling on q small silver
mirror was counted, and, by simple
calculation, the amount in the quantity
of air originally admitted thus esti-
mated. The following are some results
obtained: 1t was found that the air out.
side during rain contained per cubic
inch 521, 900 dust-particles; that during
fair weather the number present was
,oopa than four timaa that amount.