67 



permanent storage, pour off the alum solution and place successively 

 in 67% and 82% alcohol. 



For temporary examination, tease out a portion of the muscle in 

 water, separating the fibers carefully by means of needles ; cover and 

 examine. 



Permanent preparations, (a) unstained. After teasing out with 

 the needles drain off the water and add a small drop of glycerin 

 or glycerin-jelly; cover, and seal after first properly cleaning ( 162, 

 163) . (b) stained. Either employ the nitric acid method given above 

 or (better; Badertscher) dissociate at incubator temperature (about 

 38 C.) in a sat. solution of mercuric chlroid with 10% of strong nitric 

 acid added. Test at intervals and when dissociation has proceeded 

 far enough, wash out the dissociator with water and 67% alcohol. 

 Stain with carmine or hematoxylin. Mount in glycerin ( 154-), 

 glycerin -jelly ( 155), or dehydrate, clear and place in dilute balsam 

 ( 157- Cf. 215). 



(b) Potassium hydroxid. Place in the fluid small pieces of 

 the heart muscle of a fetal, new-born or young animal; after 10 or 15 

 minutes, the tissue should be tested with needles at intervals of about 

 five minutes, so that the action may not be too prolonged; probably 

 15 to 30 minutes will suffice. As soon as the elements separate 

 readily, pour off the caustic potash solution and add an abundance 

 of 60% solution of potassium acetate (potassium acetate, 60 grams; 

 distilled water, 40 c. c.). Take small fragments and tease them in 

 this solution, or shake them in a vial, until the 'cells' are separated 

 from each other. 



For temporary examination, cover, in a drop of the potassium 

 acetate solution. For permanent preparations, drain off the potas- 

 sium acetate solution and add a small drop of glycerin or glycerin- 

 jelly. 



Stained preparations. Pour off the potassium acetate solution 

 and add a half saturated solution of alum, letting it remain for 24 

 hours or longer. Tease in water, stain with hematoxylin or carmine, 

 wash away the stain with water, and add a drop of glycerin or gly- 

 cerin-jelly. Cover and seal ( 162 ). 



If a large amount is desired, the tissue may be carried through 

 the various steps in a vial. 



190. Sections. To bring out the structure of the fibrillae 

 picro-aceto-formol ( 17) or an alcoholic fixer ( 23, 24) is preferable 



