. The microscope and its revelations. e T//. which, by means of a vernieron the object-holder, enables the thickness of the section to lie readoff. The bottom plate is at once a base and a r« ceiver for the drippingspirit, oil, «\:c. 462 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS For fastening the knife a thumb-screw, 0, fig. 391, serves; hutin the modified form of the instrument designed by the ZoologicalStation, Naples, this is replaced by a single head-screw. C, fig. 392,which is provided with holes and tightened by means of a lever;and to give greater freedom to the iise of the knife
. The microscope and its revelations. e T//. which, by means of a vernieron the object-holder, enables the thickness of the section to lie readoff. The bottom plate is at once a base and a r« ceiver for the drippingspirit, oil, «\:c. 462 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS For fastening the knife a thumb-screw, 0, fig. 391, serves; hutin the modified form of the instrument designed by the ZoologicalStation, Naples, this is replaced by a single head-screw. C, fig. 392,which is provided with holes and tightened by means of a lever;and to give greater freedom to the iise of the knife there are severalholes drilled and tapped into which this screw fits. The knives of the form A, fig. 391, are generally screwed directlyto the knife-carriage, and are used for cutting very large sections, theoblique position shown in the figure being the one that is generallyindicated for the cutting of very large objects. This knife is nowseldom used except in pathological observations and in studies on thecentral nervous PIG. 392. — The Thoma microtome with the usual zoologists knife. knife, however, is also made upon another model, E, fig. 392 ;it then has a, special holder «, in which it is secured in a conical slitby the screws ft, ft1, and firmly held. For deep objects requiring considerable length to cut from, thereare plates provided for elevating the knives and the knife-holders. The knife-holder shown in fig. 392 can be rotated round the axisformed by the screw c. This allows of any degree of slant orobliquity of direction being given to the knife, from the str ctlyi raiis\ersal position shown in fig. 392 up to and beyond the slantingposition shown in fig. 391. But it provides no means of alteringthe till of the blade, that is, of elevating or depressing the back ofthe blade relativelv to its edge— a point of considerable importance,to which we shall return later on. To meet this difficulty, themaker (It. I iing. 12 Landhausstrasse, Heidelberg ; his i
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
