ZOOLOGY AND BOTANY, MICBOSGOPY, ETO. 



143 



C3) Cutting, including- Imbedding- and Microtomes. 



Minot's Automatic Microtome.* — The microtome of Dr. Minot is, 

 in the opinion of Mr. J. S. Kingsley, the best of the automatic forms. 

 Equipped with it and a Thoma or Schanze instrument for celloidin 

 sections, any laboratory may be considered as well prepared for any 

 ordinary section work. 



In the Minot microtome, the general features of which can be seen 

 from fig. 27, the knife is stationary, while the object is moved. Motion 



Fig. 27. 



is communicated either by a crank or by a belt to the balance-wheel from 

 a water-motor. Each revolution of the shaft raises and lowers the 

 object-carrier, the section being cut on the downward stroke. The 

 object-carrier is advanced towards the knife when at its extreme height, 

 by means of a micrometer screw placed between the ways on which it 

 runs. This screw has threads • 5 mm. apart, and the large wheel Z 

 which turns the screw bears 300 teeth upon its margin. This wheel is 

 turned by means of a pall which strikes the upright lever H, seen in 

 the fig., while a set-screw E allows the pall to engage from one to twelve 

 teeth at a revolution. Thus the instrument has a capacity of cutting 

 sections from 0*04 mm. to 0"0033 mm. as desired. The object P im- 

 bedded in paraf&n is soldered with the same material to one of the 

 section-holders, and this is then placed in its proper socket and clamped. 



* The Microscope, viii. (1888) pp. 241-2 (1 fig.) ; and Zeitschr. f. Wiss. Mikr., 

 V. (1888) p. 474 (1 fig.). 



