128 * PRACTICAL HISTOLOGY. 



tions both of the cerebro-spinal and of the sympa- 

 thetic nerves there will be seen, especially in those 

 prepared with osmic acid, besides the actual nerve- 

 fibres, in the first place, a quantity of connective 

 tissue, for the most part of the nature of areolar 

 tissue, which formed a general ensheathment for 

 the nerve, and sent partitions in between its several 

 bundles or funiculi ; secondly, the special sheaths of 

 the funiculi, which become torn and stripped away 

 in the process of teasing, and which look like flat 

 bands composed of an almost homogeneous substance, 

 but pervaded by a network of fine elastic fibres and 

 with round or ovalish nuclei scattered upon them 

 here and there. Thirdly, there will be seen running 

 along close to and surrounding the nerve-fibres them- 

 selves very delicate, nearly straight fibrils of con- 

 nective tissue, with here and there the nucleus of 

 a connective tissue corpuscle. These three forms 

 of connective tissue represent respectively the epi- 

 rieurium (cellular sheath); the perineuriurn (neuri- 

 lemma); and the endoneurium, or tissue within 

 the funicular ; but their relative situation and 

 arrangement, as well as the lamellated structure of 

 the perineurium, can only be properly displayed by 

 transverse sections of a nervous trunk, the mode of 

 preparing which will not be treated of until the 

 general directions for the preparation of sections have 

 been given. 



Preparation 4. But the cell-outlines on the 

 lamellae of the perineurium may be shown by the 

 silver method. For this purpose either a very small 

 nerve is chosen and a piece of it is removed and 

 immersed for ten minutes in half per cent, silver 

 nitrate solution, after which it is washed in distilled 

 water and exposed in glycerine to the light ; or, 

 should it be wished to prepare a larger nerve con- 

 sisting of more than one funiculus, this is carefully 

 dissociated in a few drops of the silver solution, and 

 after a like treatment is also to be mounted in 

 glycerine and exposed to the light. After a few 



