(A full description accompanies each instrument.)
76. =Hand-Spectroscope=, Browning's, for spectroscopic examination of the blood =12.--=
76a. =Hand-Spectroscope= with comparison prism, mirror, and holder for vials =16.--=
77. =Thoma's Haemacytometer= consists of an object glass with carefully constructed cell, a ground absolutely plane coverglass and two pipettes for mixing the blood and saline solution used in the examinations. One of these pipettes, for estimating the number of red corpuscles is so graduated as to permit dilution of the blood 100 or 200 times as required; the other, for counting the white corpuscles (leucocytes), is graduated for dilution of the blood 10 or 20 times.
The volume contents of the pipettes are most carefully determined and the depth of the cell is established by accurate micrometric measurement, thus permitting very exact observations by means of this instrument.
(A full description with each instrument) =14.50=
78. =Mixing-Pipette for white corpuscles= =3.60=
79. =Mixing-Pipette for red corpuscles= =3.60=
80. =Thoma counting chamber, with coverglass= =5.75=
81. =Türck counting chamber with coverglass= =7.25=
[Illustration: Counting chamber after Thoma after Türck.]
82. =Ehrlich's Eye-piece= is provided with a diaphragm having a square opening, the size of which is regulated by a small lever.
This eye-piece is designed to facilitate the estimation of the relative numbers of red and white blood corpuscles in dry preparations.
Full directions accompany each instrument =12.--=
82a. =Apparatus= for the clinical determination of the alcalinity of the blood, after Prof. C. S. Engel.
The following parts compose the apparatus:
1) a capillary pipette so graduated as to permit the dilution of 0,05 cc. blood from the finger, up to 5 cc. with distilled water.
2) a beaker, for the reception of the diluted blood.
3) a burette mounted on stand, capacity 10 cc. Full directions accompany each outfit. Price in box =8.--=
[Illustration: Screw Micrometer Eye-piece.]
83. =Screw-micrometer eye-piece= for accurate measurement of large objects. Between the eye lens and the collecting lens of a Huyghenian ocular there is a millimeter scale etched on glass, above which is a moveable indicator whose position is controlled by a micrometer screw to which a graduated drum is attached. The value of each graduation on the drum (about 1/20 of the micrometer value of the objective) must be determined for each combination of ocular and objective by means of the stage micrometer. The eye lens of the ocular is moveable to permit accurate focus upon the scale. The apparatus slips into the tube of the microscope like any ordinary eye-piece and is fixed in position by a thumb-screw at the side =20.--=