. The microscope and its revelations. arly parallel to the first., but makes a downward turn just above(lie centre of the slide plate, and is terminated by an ivory knob ;this wire is pressed upwards by a spring beneath it. whilst, on theother hand, it is made to approximate the lower by a milled headt urning on a screw, so as to hring its ivory knob to bear with greateror less force on the covering-glass. The special use of this arrange-ment will be explained hereafter. ARRANGEMENTS FOR DISSECTING 455 Dissecting Apparatus.—The mode of making a dissection formicroscopic purposes must be determ
. The microscope and its revelations. arly parallel to the first., but makes a downward turn just above(lie centre of the slide plate, and is terminated by an ivory knob ;this wire is pressed upwards by a spring beneath it. whilst, on theother hand, it is made to approximate the lower by a milled headt urning on a screw, so as to hring its ivory knob to bear with greateror less force on the covering-glass. The special use of this arrange-ment will be explained hereafter. ARRANGEMENTS FOR DISSECTING 455 Dissecting Apparatus.—The mode of making a dissection formicroscopic purposes must be determined by the size and characterof the object. Generally speaking, it will be found advantageous tocarry on the dissection under water, with which alcohol should bemingled where the substance has been long immersed in spirit. Thesixe and depth of the vessel should be proportioned to the dimensionsof the object to be dissected ; since, for the ready access of the handsand dissecting instruments, it is convenient that the object should. FIG. 387.—Swifts Stephenson binocular dissecting microscope. neither be far from its walls nor lie under any great depth of there is no occasion that the bottom of the vessel should !><•transparent, no kind of dissecting trough is more convenient thanthat which every one may readily make for himself, of any dimen-sion he may desire, by taking a piece of sheet gutta-percha of adequatesize and stoutness, warming it sufficiently to render it flexible, andthen turning up its four sides, drawing out one corner into a sort ofspout, which serves to pour away its contents when it needs empty-ing. The dark colour of this substance enables it to furnish a back- 456 PEEPAEATION, MOUNTING, AND COLLECTION OF OBJECTS ground, which assists the observer in distinguishing delicate mem-branes, fibres, etc., especially when magnifying lenses are employed ;and it is hard enough (without being too hard) to allow of pins beingfixed into it, both f
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
