ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



245 



supporting blade, with its edge slightly projecting, and is firmly clamped 

 there by tightening the set-screw. The instrument is then ready for 

 use. In the illustration the two blades are shown clamped together in 

 position for use, but without the cutting blade inserted. When the set- 



FiG. 47. 



screw is loosened the front blade falls forward far enough to allow of the 

 insertion of the cutting blade. 



The chief merit of this instrument is that the cutting edge is always 

 satisfactory and sharp ; its defect is the shortness of the blade, but for 

 student work the length is found to be ample. 



C4) Staining: and Injecting:. 



Staining Spirochaeta pallida Schaud.* — Th. Saling, after referring 

 to the work of various authors who have, by means of the silver method, 

 demonstrated the presence of Spirochcda in the tissues and organs of 

 animals and man, states that these spirilla should be regarded as identical 

 with nerve-end fibrillae. 



Demonstrating Negri's Corpuscles.t— Ira van Gieson states that he 

 has found in the following procedure a sure and certain method for 

 examining nervous tissue, especially in reference to the presence of 

 Negri's corpuscles. A piece of grey matter about half the size of a pea 

 is placed upon a slide, and covered with a slip. Gentle pressure is 

 exerted on the slip, and then traction made by drawing the slip slowly 

 along the slide. An excellent preparation, in which many nerve-cells 

 preserve their integrity, is thus obtained. 



For the sympathetic nervous system and for the spinal ganglia this 

 method is less suitable, owing to the presence of the connective-tissue 

 element ; fair preparations of these parts can, however, be made. Smears 

 produced by the foregoing method may be air-dried or fixed for a few 

 seconds in methyl-alcohol. They are then stained in the following 



• Centralbl. Bakt., Ite Abt. Orig., xlii. (1906) p. 120. 

 t Op. cit., xliii. (1907) pp. 205-6. 



