APPENDIX 293 



piece of tissue so treated should be not more than 1 to 2 mm. 

 square. 



Osmic acid, "I to 1 p.c., and dilute alcohol, 30 to 35 p.c., are 

 dissociating fluids of general application. After staying a short 

 time in osmic acid, or a day or two in dilute alcohol, the pieces 

 may be placed in picrocarmine for a day or two and teased in 

 dilute glycerine (cp. pp. 93, 218). 



The following agents are mentioned in the text ; picric acid 

 (tendon) p. 71 ; 35 to 40 p.c. caustic potash (muscle) pp. 94, 96, 

 106, (horny layer of skin) p. 214 ; 20 p.c. nitric acid, 1 p.c. 

 potassium bichromate (muscle) p. 97 ; 5 p.c. neutral ammonium 

 chromate (mucous glands) p. 160, (kidney) p. 197 ; hydrochloric 

 acid (kidney) p. 199 ; 5 p.c. chloral hydrate (serous cells) p. 164 ; 

 water (basket cells) p. 164. 



Besides these may be used, -02 p.c. potassium bichromate and 

 "02 p.c. chromic acid (nerve-cells of central nervous system). A 

 mixture consisting of 5 c.c. 'of a saturated solution of each 

 of the following : neutral ammonium chromate, phosphate of 

 potash, sulphate of soda with 100 c.c. of water (Landois). After 

 1 to 3 days in this the piece of tissue is placed for a day in dilute 

 picrocarmine. It has been chiefly recommended for the central 

 nervous system. 



C. Teasing. A small piece of tissue only should 

 be taken. 



As a rule it is best to tease in the fluid in which 

 the tissue has been preserved, but it may generally 

 be teased in dilute glycerine or in glycerine. 



The teasing is as a rule easier if no more fluid is 

 taken than that which clings to the piece of tissue ; 

 when the teasing is complete, a small drop of fluid is 

 placed on the centre of the cover-slip, and this is 

 lowered on the specimen. 



It is important to place the slide on an appropriate 

 ground ; if the object is of a light tint, the slide 



