A i ACE RATION, DIGESTION, AND CORROSION. 275 



after twenty- four hours, 50 per cent, glycerin, changed till the acid is 

 removed. 



539. Hydrochloric Acid. KONIGSTEIN (Sitzb. Akad. Wien, Ixxi, 

 1875) takes (for gold-impregnated cornese) equal parts of the concen- 

 trated acid, glycerin, and water; FREUD (ibid., Ixxviii, 1879, p. 102, for 

 nerve-impregnations) 10 parts of acid, 7 of water, 3 of glycerin; and 

 SCHUBERG and SCHRODER (Zeit. iviss. Zool., Ixxvi, 1904, p. 516) take 

 (for fresh muscles of Hirudinea) hydrochloric acid of 5 per cent. 



510. BELA HALLER'S Mixture (Morphol. Jahrb., xi, p. 321). 

 -One part glacial acetic acid, 1 part glycerin, 2 parts water. 

 For the central nervous system of Mollusca a maceration of 

 thirty to forty minutes may be sufficient. 



541. Sulphuric Acid (RANVIEE, Traite, p. 78). Macerate for 

 twenty-four hours in 30 grins, of water, to which are added 



4 to 5 drops of concentrated sulphuric acid. Agitate. For 

 nasal mucosa, crystalline, retina, etc. 



ODENIUS found very dilute sulphuric acid to be the best 

 reagent for the study of nerve endings in tactile hairs. He 

 macerated hair-follicles for from eight to fourteen days in a 

 solution of from 3 to 4 grains of " English sulphuric acid ' 

 to the ounce of water 



Hot concentrated sulphuric acid serves to dissociate horny 

 epidermic structures (horn, hair, nails). 



542. Oxalic Acid. Maceration for many days in concen- 

 trated solution of oxalic acid has been found useful in the 

 study of nerve-endings. 



543. SCIIIEFFERDECKER'S Methyl Mixture (for the retina) 

 (Arch. mik. Anut., xxviii, 1886, p. 305). Ten parts of gly- 

 cerin, 1 part of methyl alcohol, and 20 parts of distilled 

 water. Macerate for several days (perfectly fresh tissue). 



544. GAGE'S Picric Alcohol (Proc. Amer. Soc. of Microscopists, 

 1890, p. 120). 95 per cent, alcohol, 250 parts; water, 750; 

 picric acid, 1. Recommended especially for epithelia and 

 muscle. A few hours suffice. 



545. Chloral Hydrate. In not too strong solution, from 2 to 



5 per cent, for instance, chloral hydrate is a rnild macerating 



