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LESSON XXII 

 MUSCLE AND NEBVOUS TISSUES 



1. A rabbit has been killed and its muscles washed free from blood by a 

 stream of salt solution injected through the aorta. The muscles have been 

 quickly removed, chopped up small, and extracted with 5-per-cent. solution 

 of magnesium sulphate. This extract is given out. 



2. The extract will probably be faintly acid. The acid is lactic acid. It 

 may be identified by the following reaction : — 



A solution of dilute ferric chloride and carbolic acid is made as follows : — 



10 c.c. of a 4-per-cent. solution of carbolic acid. 



20 c.c. of distiUed water. 



1 drop of the hquor ferri perchloridi of the British Pharmacopoeia. 



On mixing a solution containing a mere trace (up to 1 part in 10,000) of 

 lactic acid with this \iolet solution, it is instantly turned yellow. Lar^^er 

 percentages of other acids (for instance, more than 0*2 per cent, of hydro- 

 chloric acid) are necessary to decolorise the test solution. 



3. The coagulation of muscle is very like that of blood. This may be 

 shown with the salted muscle plasma (the extract given out) as follows : 

 Dilute some of it with foiu" times its volume of water; di\-ide it into two 

 parts ; keep one at 40° C. and the other at the ordinary temperature. Coagu- 

 lation, that is, formation of a clot of myosin, occurs in both, but earliest in 

 that at 40° C. 



4. Add a few drops of 2-per-cent. acetic acid to some of the extract ; a 

 stringy precipitate of myosinogen is produced. 



5.9Eemove the clot of myosin from 3 ; observe it is readily soluble in 

 10-per-cent. sodium chloride, and also in 0'2-per-cent. hydrochloric acid, 

 forming syntonin. 



6. Perform fractional heat coagulation — 



(a) With the original extract. Coagula are obtained at 47°, 56°, 63°, 

 73° C. 



(6) With the liquid (salted muscle serum) in 3, after separation of the 

 clot. Coagula are obtained at 63° and 73° C. 



(c) With muscle extract which has been saturated with ma<mesium 

 sulphate and filtered. The globulins are thus separated. Coagulation now 

 occurs at 73° C, but the amount of coagulum is small. 



