NUTRITION OF MUSCULAR TISSUE. 811 



The quantity of albumen diminishes, though only to an inconsiderable ex- 

 tent (Helmholtz, Ranke, Nawrocki). The Heart in the case of the Dog in 

 comparison with the muscles of the extremities contains much less albumen. 

 The heart yields much more warm alcohol and less watery extract than the" 

 quiescent, and even than the tetanized muscles of the extremities. The 

 alcoholic extract of tetauized muscle, and especially of the heart, contains 

 more nitrogen than that of quiescent muscle. 1 It is remarkable that highly 

 oxygenated blood, such as is the condition of the blood in apncea, renders 

 both the nerves and muscles unexcitable. 2 



662. Numerous experimenters 3 have shown that the contraction of mus- 

 cular tissue is accompanied by the production of a considerable amount of 

 heat. Thiry and Meyersteiu found that on tetanizing the gastrocueraius of 

 a frog for ten minutes the temperature rose 0.073 0.119 Centigrade, or 

 about one-fifth of a degree Fahr. Helmholtz estimated the rise of tempera- 

 ture in the same case at rather less than one-third of a degree Fahr. In 

 warm-blooded animals the heat generated is much greater. Billroth and 

 Fick* observed a rise of 5 C., or more when tetanus was maintained for ten 

 minutes. The degree of heat developed is dependent upon the tension of the 

 muscle, upon the amount of work done, and upon the condition of freshness 

 or exhaustion of the muscle. With the increase of the tension the amount 

 of heat generated is augmented, so that a muscle contracted to the utmost, 

 supposing its excitability and the stimulus to remain the same, develops the 

 maximum of heat ; hence the whole amount of heat generated increases with 

 the amount of work done, though a portion is derived from the contraction 

 of the muscle itself. The temperature falls rapidly with increasing exhaus- 

 tion, and the amount generated is inappreciable to our present means of re- 

 search before the muscle has quite lost its power of contraction. Solger and 

 Meyerstein and Thiry have observed that at the commencement of contrac- 

 tion a muscle becomes sensibly cooler than before. This effect lasts several 

 seconds, and may perhaps be attributed to a diminution of the specific heat 

 of muscle in contraction ; it is followed by a gradual increase in temperature, 

 which, if the muscle be tetanized, continues for some time after contraction 

 has ceased ; and proceeds, in all probability, partly from the continuance of 

 a more energetic process of oxidation, indicated by the increased production 

 of carbonic acid, and partly from an increased flow of blood through the 

 vessels of the muscle. According to Meyersteiu and Thiry, the amount of 

 heat generated is always in proportion to the amount of work done ; whilst 

 Heideuhain maintains that the relation between the two is inverse after a 

 certain point has been reached. He notices also that less heat is developed 

 if the muscle be allowed to shorten, and thus to perform work, than if it be 

 prevented from shortening, and this may reasonably be explained on the 



1 See Danilewsky, Centralblatt, 1872, p. 433; and Griitzner, Ueber einige Chem. 

 React, des that. u. unthat. Muskels., Pfliiger's Archiv, Bd. vii, p. 254, who shows 

 that quiescent muscle is capable of oxidizing pyrogallic acid, whilst tetanized muscle 

 is incapable. 



2 See v. Bezold and Blobaum, in the Wurzburg. Physiol. Untersuch., Heft 1, 

 p. 66, and Mayer and Bascb, Sitz. d. kais. Acad. d. Wiss. zu Wien, 1870, p. 837. 

 For the phenomena of exhaustion in muscle, sae Volkmann, in Pfliiger's Archiv, 

 Bd. iii, p. 372. 



3 Helmholtz, Mailer's Archiv, 1848, p. 144; Solder, Studien des Physiolog. Insti- 

 tuts. zu Breslau, 1863, p. 12y; Meyerstein and Thiry, Zeits. fiir rat. Med., Bd. xx, 

 1803, p. 45; Heidenhain, Essay on the Theory of Muscular Force, Breslau, 1864, and 

 Mechanische Leistung, Warme-entwicklung und Stoffumsatz, 1864; Dybkowsky and 

 Fick, Vierteljahrschrift der Naturforsch. Gesell. in Zurich, 1867; Schi'fler, Pfliiger's 

 Archiv f. Physiol., 1868 ; and Miiller's Archiv, 1868, p. 442. 



4 Wundt, Physiologic, 1873, p. 536. 



