402 CHEMISTRY OF RESTING MUSCLE. [BOOK I. 



section of their nerves is less venous than that flowing from quite 

 normal muscles 1 . We are naturally led to compare this with the 

 fact which we already know, that the blood from contracting muscles 

 is far more venous than that from the same muscles in repose, and to 

 ask whether the cause is not the same in both cases. In short, do 

 the nervous centres exert a tonic influence, automatic or reflex, over 

 the muscles, keeping them constantly in a state of partial contraction 

 at the expense of certain chemical decompositions ? Such a tonus 

 has, for physiological reasons, been ascribed to voluntary muscles ; but 

 not, as yet, upon grounds which are absolutely beyond question 

 (see the various Text Books of Physiology). While, then, we may 

 bear in mind this tonic contraction of voluntary muscle, as a possible 

 or, it may be, a partial explanation, the fact itself must be taken 

 as established, that separation of a muscle from its nervous centres 

 is followed by a diminution of the normal chemical changes of repose. 

 Whether or not the nervous centres induce a constant contraction 

 of voluntary muscles, they certainly bring about a constant chemical 

 tonus (as it has been called) in the same tissues 2 . 



The method of investigating this chemical tonus has hitherto been 

 that of comparing the general excreta of the body before and after the 

 separation of large tracts of voluntary muscles from the central nervous 

 system. The excretion of the lungs was collected in an apparatus 

 for the respiration of a definite amount of gases at an unvarying 

 pressure. This apparatus, which differs from that of Ludwig and 

 Sczelkow devised for a similar purpose, will be found described in 

 the original memoirs. By means of it the oxygen consumed and 

 the carbon dioxide excreted by an animal could be measured with 

 considerable accuracy, while the arrangements were such as not 

 sensibly to impede the normal respiratory movements of the animal. 

 The apparatus was fitted with appliances for artificial respiration. 

 The separation of the muscles from the central nervous system was 

 brought about in one of two ways: by curare-poisoning 3 , or by division 

 of the spinal cord between the cervical and dorsal regions 4 . 



A rabbit was attached to the apparatus and its respiratory exchanges 

 determined, respiration being carried on artificially to such an extent as 

 to leave the rabbit apnoeic for 3 to 4 seconds on stopping the injection of 

 air. This degree of apuoea is known not to affect the material exchanges 

 of the body 5 . The rabbit was then curarized with 2 3 mgr. of curare 

 subcutaneously injected, and its respiratory exchanges again determined. 



1 Claude Bernard, Lemons sur les proprie"tes des tissus vivants, p. 221. Paris, 1857. 



2 Bb'hrig und Zuntz, "ZurTheorie der Warmeregulation und der Balneotherapie." 

 Pfluger's Arch.f. d. ges. PhysioL, Vol. xv., 1871, p. 57. 



3 Rohrig und Zuntz, Op. cit. Zuntz, "Ueber den Einfluss der Curare vergiftung auf 

 den thierischen Stoffwechsel. " Pfl tiger's Archiv f. d. ges. PhysioL, Vol. xn., 1876, 

 p. 522. Pfliiger, "Ueber Warme und Oxydation der lebendigen Materie." Arch. f. d. 

 (jes. PhysioL, Vol. xvm., 1878, p. 247. 



4 Pfliiger, Op. cit., p. 305. 



B Finkler und Oertmann, "Ueber den Einfluss der Athemmechanik auf den Stoff- 

 wechsel." Pfluger's Arch. f. d. ges. PhysioL, Vol. xrv., 1877, p. 38. 



