ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



547 



back than in Long's microtome. On tlie pin is a brass block Mbl, 

 wbidi is movable in a horizontal plane and can be fixed by a screw S. 

 In the brass block is a solid beam B, ending in a round pin Z,. This 

 beam is penetrated at its free end by a steel screw Si, on which is 

 set a clamp Kl, movable in a backward and forward direction in a slit. 

 This is intended to hold the preparation, and can be pushed 2 cm. 

 forwards or backivards, and is movable ou the axis S^. The clamp is 

 fastened, when it has been brought to the most suitable position, by a 

 female screw SM, which acts on the axes of its two branches and 



Fig. 129. 



presses them against a metal tube E, so that after fastening displace- 

 ment is impossible. Below, the clamp communicates with a lever H, 

 which is of the same length as the clamp. A micrometer screw McS 

 presses on the lever and runs in a side-piece of the beam B. By 

 greater or less turning of this screw one can at pleasure make sections 

 of any degree of thickness. In order to be able to move the screw 

 with accuracy, a quadrant divided into 25 parts is placed on the 

 cross-beam, and a small key on the screw carries the pointer. At the 

 end of the beam is a hole, in which a long steel pin St is fixed, with 

 which the movement around the " sagittal " axis is effected. 



Schanze's Microtome. — We append fig. 130, showing Herr M. 

 Schanze's microtome,* which is deserving of record as being the 

 original form on which was founded Mr. Bulloch's instrument, as 

 well as that described ante, p. 344. Like that of Korting,! it is a 

 combination of the screw and the slide arrangement, the knife being 

 attached to a slide, while the object is raised by a vertical screw S, 

 which is graduated, each division corresponding to a rise of 1/100 mm. 

 This screw works against a plate P, which slides in a dovetail in the 

 vertical plate W and carries the clamp. Two axes at right angles, 

 controlled by thumb-screws, allow of the object-clamp being inclined 

 in any direction. There is a freezing attachment, in addition to a 

 holder for clamping hard specimens and another for objects which 

 have been hardened with any of the usual reagents. 



* Cf. Fol's Lehrbuch d. Vergl. Mikr. Anatomie, 1884, pp. 128-9 (1 fig.), 

 t See this Journal, i. (1881) p. 693. 



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