The San Francisco call. [volume] (San Francisco [Calif.]) 1895-1913, 1896-06-14

breeding bacteria and decomposing certain
substances. He also has machine for
cutting an ordinary angle worm into 10000
perfect slices.
DR.. Eisen's daily life is most simple, as
are also his tastes in other matters. He is
an early riser, and either goes direct to
his laboratory, or else out into the field to
hunt for specimens.
1t is no small undertaking to prepare
even one small slide for examination under
the microscope, and the work must be
done in a certain way or the result Is a
failure. DR.. Eisen's method of preparing
blood slides is in principle the sameas that
used by all other microscopieal investi-
gators in the world.
The first thing to do is to get the speci-
men. Say it is to be that of the ordinary
water-dogs that are found in plenty in the
streams about San Francisco. DR.. Eisen
always does his own collecting, for there
are many things to be considered. The
age of the reptile is of the greatest i'm
portance, and after the reptile is removed
from the water in net, the doctor makes
careful examination. Should the creature
prove to be too old, he replaces it in the
pool, and it loses no time in finding a
comfortable place under rock.
It is rather a remarkable thing that
when DR.. Essen is collecting these crea-
lures they show little fear of him, and
even when he has them in his hands will
lie quiet until he either puts them in a
bottle or retdrns them TO their native ele-
ment in the pool.
Having satisfied himself with a speci-
men DR.. Esen put it into specially pre-
pared water-bottle. He usually takes the
water-dogs little too young and keeps
them in his laboratory until they are the
right age for experiments.
Having ehloroformed the reptile to be
sacrificed to science, DIR. Eisen quickly
makes an incision with a scalpel OF razor
sharpness and lays bare the tiny heart.
This he takes hold of with pair of small
tweezers and then cuts it so that the drop
or two of blood the creature possesses will
flow. He then rapidly rubs the heart over
a number of clean glass slides that have
been warmed. This leaves an almost i'm
perceptible film of faint ruby color on
them. They are then laid away to dry for
forty-eight hours. In doing this work it
is necessary to move like lightning, as
that single drop of blood must be spread
over twenty or thirty slides within two or
three minutes, or the crimson fluid will
coagulate.
Should one of these slides be put under
a high-power microscope without further
preparation very little could be seen. The
corpuscles would show as tiny shells, but
that is all. In order to be able to see what
the blood contains the slides must be
stained" Different stains bring out diff
ferent parts. There are thousands of
stains in general use, and new ones are
being constantly discovered. 1t has been
the discovery of certain stains that have
enabled certain bacteria to be seen. For
instance, the stain that will reveal bacilli
tuberculosis would have no effect on the
cholera microbe, and vice versa. 1t was
by the discovery of new method of STAIN
ing that DR.. Essen was enabled to make
his recent great discovery.
Not only are single stains used, but they
are combined in hundreds of ways, each
producing different result. The methods
of handling the stains also vary greatly.
Some must be fixed with acid, and some
with alcohol or other chemical.
If a plate is examined before being
stained and then afterward it seems like
magic. In the first place there was almost
nothing, and in the last beautiful forms in
brilliant colors and delicate outline are
visible.
The blood from the same animal can be
put on fifty different slides, and by care
full staining can be made to give fifty diff
ferent results. In some only portions of
certain cells will appear, and in others the
cells will be invisible and only the blood
parasites show. And yet the same ele-
ments exist in the same proportion on
every one of the slides.