300 ACIDIFICATION OF MUSCLE DURING RIGOR. [BOOK I. 



the retina, &c., has been gained by researches which prove the value 

 of the conception of Du Bois-Reymond. 



Methods of Strips of red and blue litmus paper are pinned 



determining alternately in rows to a varnished board, so that the 

 the reaction edges of adjoining pieces are in contact. A section of 

 the muscle of which the reaction is to be determined is 

 then pressed firmly over the boundary of two slips. In normal muscle 

 it is then observed that both the red paper assumes a bluish tinge 

 and the blue paper a reddish tint. This so-called amphichromatic 

 or amphoteric reaction, depends upon the muscle having in reality 

 often a neutral reaction ; when this is the case, though it affects both 

 blue and red litmus paper, it does not alter the tint of violet litmus. 



When a muscle passes into the state of rigor mortis the reaction 

 becomes ipso facto decidedly acid, except in cases where the rigor is 

 brought on by plunging the muscle into hot water, when the 

 reaction is found to remain neutral or alkaline. 



It would appear that the amount of acid which can be produced 

 in a muscle when it passes into rigor is a definite quantity, doubtless 

 depending upon the quantity of the body which, by decomposing, sets 

 acid free. 



Acidifica- As was first shewn by Du Bois-Reymond, when a 



tion of mus- separated muscle is tetanized and its reaction is deter- 



cies, removed m i ne d from time to time, it is observed to become more 



from the in- , . -, i 



fluence of the and m ? re aci( ? 



Wood, when Heidenhain shewed that the amount of lactic acid 



they are formed during contraction increased with the resistance 



tetanized. which the muscle had to overcome 2 . 



It was shewn by Ranke that in this case as in tetanus there 

 is a maximum amount of acid which can be generated in the muscle 

 which is cut off from the blood-stream, and then tetanized. If two 

 muscles were taken for the determination of the amount of acid 

 formed during rigor mortis, but if one were subjected to prolonged 

 tetanus until rigor set in, whilst the other was allowed to remain 

 at rest, the quantity of acid formed in the first case would exceed 

 that formed in the second ; there is, therefore, a consumption of acid- 

 yielding substance during tetanus 3 . 



Causeof the The acidity of muscle in the state of rigor or which 



acid reaction h as b een tetanized is chiefly, if not entirely, due to the 

 wh^h^in liberation of lactic acid. In the very earliest stage of 

 the state of rigor it is probable that the acid reaction is really 

 rigor. due to an acid potassium phosphate, produced from 



the alkaline phosphate by the action of lactic acid. Soon however 

 the reaction is acid because of the presence of lactic acid. 



1 Du Bois-Beymond, Op. cit. p. 26. 



2 Heidenhain, Mechanische Leistung, p. 143 et seq. 



3 In a thesis presented to the University of Bonn on 4th June, 1880, and entitled 

 "Beitrage zur physiologischen Chemie des Muskels," Dr Joseph Warren communicated 

 preliminary observations tending to shew that the amount of lactic acid which can be 

 obtained from muscles which have been tetanized is smaller than is yielded by similar 

 muscles which have been maintained in a state of rest. 



