Microtomes: their Choice and Use 245 



pact, and well designed. The powerful jaws for grasping the 

 object can be rotated, moved vertically, and finally fixed by 

 means of the screw seen on the extreme left of Fig. 65. 

 The object standing in an inverted position upon the base 

 of the instrument to the right is a paraffin table, and fits 

 into the same socket as the jaws. Besides the orientation 

 just mentioned, the object- jaws can be moved in an arc at 

 right angles to the tramway upon an axis governed by the 

 thumb-screw seen to the right of Fig. 65, immediately 

 below the long lever. The other thumb- screw immediately 

 below and to the left of the last-mentioned governs the 

 same kind of movement, but parallel to the tramway. By a 

 combination of these movements the object may be easily 

 and rapidly placed, and firmly fixed in any position that 

 the knife-edge could reach. Added to this, if the last 

 thumb-screw mentioned be taken off, the whole orientating 

 apparatus may be removed and put in the reverse way, 

 bringing the object- jaws considerably nearer the right-hand 

 side of the microtome. Fig. 66 exhibits the orientating 

 apparatus reversed in comparison with Fig. 65. This re- 

 versal makes not the slightest difference in the movement 

 obtainable for orientation, and is a great advantage to the 

 worker. When cutting with the knife set obliquely to the 

 tramway, as in cutting by the wet method, the arrangement, 

 as in Fig. 65, allows more travel to the knife-carrier in a 

 direction to the right of the object. When cutting objects 

 in paraffin with the knife set at right angles to the tram- 

 way, the reversal of the object-holder allows more travel to 

 the knife-carrier in a direction to the left of the object 

 (Fig. 66). The long lever to the right of the illustrations 

 immediately under the maker's name is a coarse adjust- 

 ment for rapidly moving the whole of the orientating 

 apparatus up or down in its slide. The use of this will 

 be described in the chapter on cutting. About 22 milli- 

 metres of material may be cut without readjustment of the 

 object-holder. The feed arrangement is by a micrometer 

 screw pushing up the object-carrier in its vertical slide. 



