110 APPENDIX TO THE HISTOLOGICAL SECTION. 



(c) It is best to fix and harden first by means of Miiller or corrosive 

 and subsequently to decalcify with 2P- C - HNO., or IP- C - HC1. After- 

 harden with alcohols. 



15. Sulpho-picpic Acid (Kleinenberg). To a saturated aqueous, 

 solution of picric acid add 2P- C - H 2 S0 4 , let the pp settle for an hour, 

 filter, and add three parts of water. The pieces must not be large,, 

 treat from 3 to 6 hours, followed by increasing alcohols, by which all 

 colour should be removed. Tissues stain well afterwards. Good for 

 young tissues. 



16. (a) Fopmol (Formaline) is a saturated solution of formaldehyde in 

 water, and contains 4QP- C - of the gas. This reagent penetrates well 

 and hardens central nervous tissue rapidly. A 1QP- C - solution in 

 water (formol 1 part, water 9 parts) is commonly employed for the 

 first 24 to 48 hours, to be followed by SP- C - solution until the required 

 density is acquired, when a 2^P- C - solution may be used for subsequent 

 preservation. Large masses of tissue are soon penetrated and may be cut 

 by freezing in gum without impregnation. 



(b) Fopmol Miiller (Orth quoted by Kahlden). (1 part formol, 

 50 parts Miiller.) This requires to be fresh, as the mixture becomes 

 turbid and deposits (even in the dark) after about four days. For 

 rapid hardening of tissues at 35 C. in 3 to 6 hours. The pieces are then 

 dipped into gum, frozen and cut or followed by thorough washing and 

 after-treatment with alcohol. 



STAINING. 



17. Borax eapmine (Grenadier). Carmine 3 s, borax 4 , water 

 100 cc . Warm moderately until the carmine is dissolved. When cold add 

 an equal volume of 70 P- C - alcohol ; or the latter may be omitted. 

 A good bulk stain, though rather slow in action, 48 hours to a week, 

 or more. After- treat) in acid alcohol, 1 p - c - HC1 in 70 P- C - alcohol for 

 24 hours, this concentrates the stain on the nuclei and gives a 

 redder tint. 



18. Alum eapmine. Boil 1% carmine in 100 cc of P- C potash 

 alum for 20 minutes. Does not overstain and is not alkaline. The 

 addition of 10 p - c - glacial acetic acid improves its penetrative power. 



19. Picpocapmine, picrocarminate of ammonia (Ranvier). Car- 

 mine dissolved in ammonia is poured into a saturated solution of picric 

 acid in water until saturation is reached, which is indicated by the 

 appearance of a precipitate. Evaporate the mixture to one-fifth its 

 bulk, in a drying chamber. When cool, filter, and evaporate the 



