26 PRACTICAL HISTOLOGY. 



8. Landois' Fluid : 



Neutral ammonium ehromate . . .5 grms. 



Potassium phosphate 



Sodium sulphate . . . . ,, 



Distilled water . . . . 100 cc. 



This is specially useful for the central nervous system. Small 

 pieces must lie in it for 1-5 days. (See Lesson on Nervous System.) 



9. Methyl Mixture or Schiefferdecker's Fluid : 



Methylic alcohol . . . . 5 cc. 



Glycerine . . . . 50 ,, 



Distilled water ..... 100 ,, 



It is better to prepare it fresh, hut it can he preserved in a 

 glass-stoppered bottle. The methylic alcohol rapidly 

 evaporates. The tissues remain in it for several days, 

 and it is specially useful for the retina and central 

 nervous system. I find that it isolates epithelial cells 

 in one to two days. It acts very much like Ranvier's 

 alcohol. 



10. Other fluids are referred to in the text, e.cj., 

 baryta water, and 10 per cent, sodic chloride for 

 tendon. This dissolves the cement substance of epi- 

 thelial cells and the mucinoid cement of connective 

 tissue. 



11. Digestion Methods, both gastric and tryptic, 

 FIQ. 27. Glass arc used (see text). 



Thimble for ^ ie s P ec i a l llses ^ ^ ne above-named fluids are 

 dissociating referred to in text under the tissues or organs, for 

 o\\ss~ue eS which each is specially adapted. 



General Directions for Dissociating Tissues. 

 Always use a very small piece of the tissue or organ, and place it 

 in a not too large quantity of the dissociating fluid. Small glass 

 thimbles (fig. 27) are very useful for this purpose. 



V. HOW TO TEASE A TISSUE. 



To separate by means of needles the elementary parts of a tissue 

 is by no means an easy task. The tissue must be seen distinctly, 

 and the needles must be so used as not to break up the parts, but 

 only to separate them. The process may be done by the unaidod 

 eye or with the aid of a lens or dissecting microscope (figs. 24, 25). 

 The light must be good, and an appropriate background for the 

 object should be selected. If the tissue is colourless, use a black 



