lOO PRACTICAL PHYSIOLOGY. [XIV. 



duced on the red paper, showing that the muscle is alkaliTie during 

 life. The blue paper is not affected. 



{b. ) Test the reaction of a piece of butcher's meat ; it is intensely acid, due 

 to sarco-lactic acid. 



(c*. ) Dip the other gastrocnemius into water at 50° C. until rigor caloris 

 sets in. Test its reaction ; now it is acid. 



(rf, ) Boil some water, and plunge into it any other muscle of the same 

 frog ; it is alkaline. 



{c. ) Tetanise a muscle for a long time ; its reaction becomes acid. 



2. Watery and Saline Extracts. 



{a.) Mince some perfectly fresh muscles from a rabbit or dog. 

 Extract with water, stirring from time to time. After half an 

 hour, pour off, and filter the watery extract. Re-extract the 

 remainder with water untn the extract gives no proteid reactions. 

 For the purposes of this exercise, half an hour is sufficient. Keep 

 the filtrate, which contains the substances soluble in water. 



{b.) Take some perfectly fresh muscle from a rabbit, rub it up 

 with sand in a mortar, and extract it with a large volume of 13 

 p.c. solution of ammonium chloride, or 10 p.c. NaCl, or 5 p.c. 

 MgSO^. Stir occasionally, and allow it to extract for an hour. A 

 stronger extract is obtained if it be left until next day. Pour off the 

 fluid, keep it, as it contains the substances soluble in saline solutions 

 — the globulins. 



3. With the filtrate of 2 (a.)— 



(a.) Test for proteids, e.g., serum-albumin. 



(6.) Test the coagulating point of the proteids it contains (45* 

 and 75" C). 



(c.) Add crystals of ammonium sulphate to saturation, which 

 precipitates all the proteids. 



4. With the filtrate of 2 (^.)— 



(a.) Pour a few drops into a large quantity of water; observe 

 the milky deposit of myosinogen. The precipitate is redissolved 

 by adding a strong solution of common salt. 



(b.) Test the coagulating point. Foiu* proteids are coagulated 

 by heat at 47°, 56°, 63°, and 73° C, an albumose being left in 

 solution. The fluid is acid in reaction. 



(c.) Saturate the filtrate with crystals of sodic chloride or 

 ammonium chloride. The myosinogen is precipitated. 



(d.) Collect some of the precipitate of 4 (<-.), dissolve it with a 

 weak solution of common salt, and test for proteid reactions 

 (Lesson I. 1). Repeat 3 (c). 



(e.) Suspend in the fluid a crystal of rock-salt; the latter soon becomes 

 coated with a deposit of myosinogen. 



