158 PRACTICAL HISTOLOGY. 



service for softening white fibrous tissue (Ranvier), when, 

 e.g., it is desired to separate muscular fibres. It also 

 softens the cementing matter between epithelial cells, and 

 thus permits of their ready isolation. 



285. Boiling by converting white fibrous tissue into 

 gelatine is useful for permitting of the isolation of mus- 

 cular fibre in the making of coarse dissections. 



286. Dilute sulphuric acid. White fibrous tissue is 

 rapidly dissolved by maceration, at a temperature of 46C., 

 in dilute sulphuric acid (commercial acid i part, water 

 1000 parts). This method is very useful in making coarse 

 dissections of muscle. The cement connecting the fibres 

 of the lens may be dissolved by boiling for five or ten 

 minutes in dilute sulphuric acid (i per cent). 



287. Acetic acid and glycerine (glycerine i ounce, 

 glacial acetic acid 5 drops) is recommended by Beale for 

 softened white fibrous tissue, in tracing the course of nerve 

 fibres with high powers. The white fibrous tissue is ren- 

 dered very transparent and gelatinous, while medullated 

 nerve fibres are rendered granular. In this way the nerve 

 elements are readily recognised. This mode of tracing 

 fine nerves has now, however, been largely superseded by 

 the method of staining them with chloride of gold. 



288. Iodised serum ( 267) is recommended by Schultze 

 for the maceration of white nerve fibres. The cement be- 

 tween the fibrils is softened and dissolved. 



289. Chromic acid, potassium bichromate. Although 

 these substances have already been described as hardening 

 agents, they are also used for softening connective substances. 

 per cent solution of chromic acid softens the material at 

 the sides of the prisms of striped muscle, and so facilitates 

 cleavage into fibrillae ( 141). 



A very dilute solution of chromic acid (one or two parts 

 to 10,000 of water) is also an excellent macerating agent 

 for the separation of epithelial cells. So also is a very dilute 

 solution of potassium bichromate (one or two parts to 

 1000 of water). These very dilute fluids should have a 

 few drops of carbolic acid added to prevent putrefaction of 

 the tissue. 



