On adding caustic potash to the precipitate it will dissolve, and the solution formed will appear greenish by transmitted and red by reflected light. This phenomenon is called the dichroism of blood. Authorities differ in opinion as to whether the colour is green by transmitted and red by reflected light, or vice versa. “As a matter of fact, the phenomenon is chameleon-like as regards colour, so that both sets of observers may be considered right or wrong” (Glaister).
Fig. 10.—Photo-micrograph of red blood corpuscles from domestic fowl, × 250.
(R. J. M. Buchanan.)
Fig. 11.—Photo-micrograph of blood corpuscles of fish, × 250.
(R. J. M. Buchanan.)
Fig. 12.—Photo-micrograph of blood corpuscles from a dried stain of the blood of a codfish, × 250.
(R. J. M. Buchanan.)
3. Add tincture of guaiacum, freshly prepared: an opaque, cream-coloured precipitate of the guaiac resin will form in the aqueous solution. On the addition of ozonic ether, turpentine, or peroxide of hydrogen, a blue colour will be produced at the junction of the fluids: proportionate to the amount of blood-colouring matter present, the blue colour will vary in intensity.