ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



669 



of the carrier is insured by its weight and by its working along the 

 triangular grooved slide-way e. In the cross pieces i k are several holes, 

 these are for the purpose of 

 altering the angle of the 

 knife c, which is fixed by 

 means of the screws I and 

 m. The angle which the 

 knife makes with the slide- 

 ways depends on the size 

 or diameter of the prepa- 

 ration, and must always be 

 so selected that the edge of 

 the knife can be used as far 

 as possible throughout its 

 extent. 



The upper part b carries 

 the micrometer screw n 

 which moves the object- 

 carrier up and down. This 

 screw has a turn of 1 mm., 

 and as the head is divided 

 into 100 parts the carrier 

 can be raised 0-01 mm. 

 The lower part of the 

 microtome can either be 

 constructed as a pan, or 

 the instrument be placed in 

 one, so that it can be made 

 to work under fluid, and is 

 therefore very useful for 

 the preparation of nervous 



tissue. In the later constructions the object-clamp is made indepen- 

 dent of the micrometer screw for its coarse-adjustment. 



Fig. 110. 



Fig. 111. 



V^i/^4). 



i^- 



ur 



J 

 J 



Accessory to the Cambridge Rocking Microtome.* — Dr. H. 

 Zwaardemaker has in conjunction with his amanuensis L. Hasselaer 



* Zeitschr. f. Wiss. Mikr., iv. (1887) pp. 465-6 (2 figs.). 



