222 



PRACTICAL HISTOLOGY. 



[XVIII. 



small part of the bone, so as to trace the nerve as far Lack as possible. Its 

 greyish gelatinous semi-transparent ganglion is seen. Remove the nerve with 

 the ganglion and place it for twenty minutes in I per cent, osmic acid and then 

 stain it in picro-carmine. Tease a small piece in glycerine, and it is by no 

 means difficult to find pyriform cells, each with a large nucleus, usually near 

 the broad end of the cell. The protoplasm frequently contains large refractile 

 granules. The straight process from the cells is readily seen, and with care 

 the spiral process also can be seen. 



The methylene-blue method (p. 192) shows very well the straight and the 

 spiral fibre. Place the fresh tissue in the methylene fluid. 



17. Isolated Cells of Sympathetic Ganglion (Mammal). (a.) Tease a sym- 

 pathetic ganglion best done after maceration for 24 hours in weak acetic acid 

 (2 drops to 100 cc. water). To isolate a cell showing its connection with a 



nerve-fibre requires much patience. 



(b.) Place a small piece of the superior 

 cervical ganglion of a rabbit in per cent, 

 osmic acid for 2-3 hours. Leave it in water 

 for a day or two to macerate, and then 

 tease it in diluted glycerine. A better plan 

 is to make an interstitial injection of the 

 osmic acid. It requires to be carefully 

 teased to get isolated cells showing several 

 nerve-fibres passing off from them. 



(H) Note the spherical cell, with a 

 nucleated capsule. It gives off many pro- 

 cesses, each of which becomes continuous 

 with a nerve-fibre, i.e., it is multipolar. 

 These cells in the rabbit usually contain 

 two nuclei (fig. 206). 



(c.) Double Impregnation Method of 

 Ramon y Cayal. It is better to use the 

 sympathetic ganglia, e.g., G. stcllatum of 

 embryos (dog, rabbit), or those of new-born 

 animals. The fresh ganglion is placed in 

 Golgi's bichromate-osmic acid fluid (3 days), 

 then wash it with distilled water and after- 

 wards with .75 per cent, silver nitrate. 

 Leave it for 1-2 days in fresh silver nitrate 

 (75 P er cent.). AVash it again, and place 

 it again in osmico-bichromate mixture (4- 

 4! days), and then again in silver nitrate. 

 Sometimes even a ''treble impregnation " is 

 useful. This process "intensivo" or 

 " impregnacion doble " we owe to R. y 

 Cayal, who has obtained good results with 

 it, and so has L. Sala, 1 whose paper 1 

 contains figures of his results and a resume 



the literature. He finds that the cells are multipolar with a single 

 unbranched process and numerous branched protoplasmic processes. 



18. Methylene-Blue Method. This is an admirable method, and depends 

 on the fact that this substance stains blue the axis-cylinders or fibrils of 

 nerves in vivo. It is applicable for studying the terminations of nerve-fibres 

 in any tissue where they terminate, and also for the connection between nerve- 

 fibres and nerve-cells. When injected into the blood-vessels of an animal, it 



FIG. 206. Isolated Nerve-Cell from 

 Superior Sympathetic Ganglion of 

 a Rabbit. /. Remak's fibres; 

 n'n'. Nuclei of these libres ; nn. 

 Nuclei of cell. 



6f 



1 Archiv ital. de Biologic, 1893, p. 439. 



