244 PRACTICAL HISTOLOGY. 



In. this way a piece of the cerebellum two or three 

 small pieces from different parts of the convoluted 

 surface of the cerebrum, the medulla oblongata, and 

 pieces of the spinal cord from the middle of the three 

 regions (cervical, dorsal, and lumbar) are to be pre- 

 pared. They should be taken from the human sub- 

 ject if possible, although it is useful to study the 

 parts, especially the spinal cord and medulla, in the 

 lower animals as well. The sections, at least those 

 of the spinal cord and medulla, may be made with 

 the aid of a microtome (see Appendix), and, after 

 being stained, are treated in the usual manner with 

 alcohol and oil of cloves, and mounted in dammar 

 varnish. Logwood may be used for the purpose of 

 staining the sections, and also carmine; but, on the 

 whole, for sections of the central nervous system, 

 some of the aniline dyes (which may for the most 

 part be employed in either alcoholic or watery solu- 

 tion) give better results. One of the best is that 

 known in commerce as aniline-blue-black, which 

 stains the nerve-cells and the axis-cylinders of a dark 

 slate-blue color. For the cerebellum a solution of 

 aniline blue is recommended. 



A double coloration by logwood and eosine (an aniline 

 dye, possessing a red color) has been recently advocated. 

 The eosine is to be used in solution in alcohol (see Appen- 

 dix). The sections are first stained with logwood, and 

 then placed in eosine. When sufficiently colored by this 

 they are passed through oil of cloves and mounted in 

 dammar. 



Preparation by Sankey's method, For the 



preparation of large sections of different parts of the 

 brain (particularly of the cerebral convolutions and 

 of the cerebellum), destined more particularly to 

 show the nerve-cells and the course and connection 

 of their offsets, there is no better method than that 

 described by Sankey (''Quarterly Journal of Micro- 

 scopical Science," April, 1876). It is shortly as fol- 

 lows: With a large and long knife wetted with 

 spirit, slices of the fresh brain (of the cerebellum 



