ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



893 



Fig. 164. 



metal, and increasing the surface exposed to the ether-spray, which is 

 applied by an arrangement of tubes supported by a rod I. The plate 

 is large enough for pieces of tissue from 

 4 to 5 mm. by 2i mm. downwards. 



General directions are added as to 

 freezing and cutting which it is un- 

 necessary to repeat here. Specimens 

 otherwise hardened, however, Dr. Roy 

 prefers to imbed in a mixture of wax 

 and olive-oil shaped in a mould to fit in 

 the frame (Fig. 164), which is made by 

 removing the plate d and adding a 

 third vertical plate c, which is fixed by 

 the screws b. A spring presses the 

 plate e forward so as to prevent any 



lateral movement of the imbedding mass. The microtome is fixed to 

 the table by a clamp with a screw the head of which is seen at m. 



Dr. Roy adds subsequently * that the essential points for which he 

 claims novelty in this microtome are the peculiar structure of the 

 object-plate to increase the surface exposed to the ether spray, and the 

 improvement in the manner of attaching the knife. 



Professor C. Weigert,f in preference to the English razor, employs 

 the knives made by Hartel of Breslau or Frank of Leipzig, for making 

 the sections, as having a perfectly level surface and not rubbing with the 

 lower surface the object which is cut. By applying the sliding principle 

 of the Rivet microtome he avoids the pressing action of the razor 

 which, for soft specimens, is so undesirable — a drawing motion being 

 thus substituted. He diminishes the area of the plate over which the 

 razor travels by bending its sides somewhat down. When usin<* the 

 sliding principle the objects must not be frozen too hard. When 

 sections have been made by the freezing plan they are examined fresh 

 or in salt solution. 



Boecker's Microtome with Automatic Knife-Carrier. J — Although 

 the microtome has now reached a high degree of perfection (writes 

 E. Boecker) many defects still exist in the usual forms, as well as in 

 those with sliding carriers for the knife. For this reason, perhaps, 

 many still prefer free-hand cutting with the razor, although it is 

 scarcely necessary to remark how little accuracy can be thereby 

 obtained, and what inferior sections of often valuable material are 

 turned out. The principal fault of the microtomes hitherto con- 

 structed, consists in the frequent tearing of cells or tissues, caused 



at least in slide microtomes — by the fact that the knife is often 

 wrongly placed and having only a forward movement, presses the 

 object rather than cuts it. It is at least expected of a good micro- 

 tome that with careful manipulation not a single section should be 

 lost, a requirement of the utmost importance in series sections, or in 



* Arch. f. Mikr. Anat., xix. (1881) pp. 527-8. 



t Arch. Path. Anat. u. Physiol. (Virchow), lxxxiv. (1881) pp. 287-90 

 % Zeitschr. f. Instrumentenk., ii. (1882) pp. 209-12 (4 figs.). 

 Ser. 2.— Vol. II. 3 



