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60 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
an outfit which cost about twenty dollars (of course not includ-
ing microscope), and gradually added one instrument after
another.
For one hundred and twenty-five dollars a laboratory may be
furnished with about all the apparatus necessary for carrying
on extensive general work, including the incubator and micro-
tome, but not the microscope.
Following is a list of the most essential apparatus
1. A microscope. I would recommend those who are anxious
to obtain a microscope at the least possible momentary expense
by all means to procure a good stand, with two objectives of low
power, and the necessary oculars to give a magnification of 200
to 300 diameters. With these one may carry on a very exten-
sive series of bacteriological investigations; in fact, with help
of the methods of pure culture, one can accomplish very much
without a microscope at all.
When, however, the question of the morpholog}' and mode of
development of bacteria, or their distrilnition in tissues, etc., is
to be considered, an oil-immersion lens will be necessary (price
S25 to §150). It is poor policy to buy a cheap stand, because it
will soon be out of order, and when subsequently one wishes to
complete the apparatus by adding new lense^, etc., it will be
found inadequate, and will have to be thrown away.
2. An incubator: zinc, ^12.50 ; copper, §35 to 8100.
3. A hot-air sterilizer for glass plates, etc., $6.
4. A steam sterilizer (Koch's Dampfcylinder), $6.
5. A spiral burner (automatic), $5.
6. A thermo regulator, §5 to 810,
7. A microtome with freezing arrangement (complete), $30.
8. Two gas-burners, %2.
9. Two dozen glass plates and benches, 81.50.
10. Six damp chaml.)ers, §3.
11. Leveling apparatus, for pouring cultures (complete), $4.
This apparatus consists of a tripod supported by three screws,
two shallow glass vessels, one slightly smaller, resting upon three
corks placed upon the bottom of the larger, a perfectly plane glass
<30ver, and a spirit-level. In use, the glass cover is first adjusted
and made perfectly horizontal by the help of the spirit-level and
60 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.
an outfit which cost about twenty dollars (of course not includ-
ing microscope), and gradually added one instrument after
another.
For one hundred and twenty-five dollars a laboratory may be
furnished with about all the apparatus necessary for carrying
on extensive general work, including the incubator and micro-
tome, but not the microscope.
Following is a list of the most essential apparatus
1. A microscope. I would recommend those who are anxious
to obtain a microscope at the least possible momentary expense
by all means to procure a good stand, with two objectives of low
power, and the necessary oculars to give a magnification of 200
to 300 diameters. With these one may carry on a very exten-
sive series of bacteriological investigations; in fact, with help
of the methods of pure culture, one can accomplish very much
without a microscope at all.
When, however, the question of the morpholog}' and mode of
development of bacteria, or their distrilnition in tissues, etc., is
to be considered, an oil-immersion lens will be necessary (price
S25 to §150). It is poor policy to buy a cheap stand, because it
will soon be out of order, and when subsequently one wishes to
complete the apparatus by adding new lense^, etc., it will be
found inadequate, and will have to be thrown away.
2. An incubator: zinc, ^12.50 ; copper, §35 to 8100.
3. A hot-air sterilizer for glass plates, etc., $6.
4. A steam sterilizer (Koch's Dampfcylinder), $6.
5. A spiral burner (automatic), $5.
6. A thermo regulator, §5 to 810,
7. A microtome with freezing arrangement (complete), $30.
8. Two gas-burners, %2.
9. Two dozen glass plates and benches, 81.50.
10. Six damp chaml.)ers, §3.
11. Leveling apparatus, for pouring cultures (complete), $4.
This apparatus consists of a tripod supported by three screws,
two shallow glass vessels, one slightly smaller, resting upon three
corks placed upon the bottom of the larger, a perfectly plane glass
<30ver, and a spirit-level. In use, the glass cover is first adjusted
and made perfectly horizontal by the help of the spirit-level and
