810 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



nal and transverse strife were much less distinct. So in persons whose lower 

 extremities have been long disused, the muscles first become pale and flabby ; 

 their bulk gradually diminishes; their contractile force progressively de- 

 creases, and at last departs almost entirely ; and their proper structure is 

 replaced by a deposit of fat, in which few or no striated muscular fibres can 

 be detected. But muscles that have for some time remained in this condi- 

 tion may be gradually brought back to their original state by exercise, pro- 

 vided that the feeblest contractility remains ; for every action which they 

 can be made to perform determines an augmented flow of blood through the 

 tissue, and gives rise to an improvement in its nutrition, which in its turn 

 increases its contractility, and renders it capable of more vigorous action. 

 This principle is of great importance in the treatment of the various forms 

 of paralysis (especially the hysterical), in which the muscles are thrown out 

 of use by the suspension of the functional power of the nerves ; for when the 

 latter have recovered their capacity, the muscles refuse obedience to their 

 stimulation, and can only be brought to act by persevering and judiciously 

 contrived exercise. 



661. Muscles exist in two states, the elongated and the contracted ; the 

 former is usually termed their state of rest, in which they immediately re- 

 spond to the application of stimuli, whether direct or indirect, by passing 

 into the active state of contraction. 1 The physical, chemical, and electrical 

 properties of muscles differ considerably in these two states. In contraction 

 the muscles become shorter and thicker, and diminish slightly in volume. 2 

 Their elasticity and electrical relations are modified, and heat s and sound 

 are produced. They absorb more oxygen. They give off, as already stated, 

 more carbonic acid. Their reaction changes from neutral or feebly alkaline 

 to acid, which, according to Rauke,* is due to the development of lactic acid. 

 They contain more creatin, grape sugar, and fat, and less glycogeu. 3 From 

 the experiments of Helmholtz, 6 which have been corroborated by Ranke, it 

 appears that the muscles of frogs long subjected to the action of an interrupted 

 current of electricity yield from 20 to 24 per cent, less of extractives soluble 

 in water, whilst those soluble in alcohol increase to a corresponding amount ; 

 the muscles also respond differently to electrical shocks. In tetanus the 

 muscles of the extremities, if the blood-current through them be preserved, 

 become more watery (Rauke). This is particularly the case with the heart. 



1 Dr. Kadcliffe (see his Epileptic and other Convulsive Diseases of the Nervous 

 System, 3d edit., 1860, and his Lectures on Epilepsy, Pain, and Paralysis, 1864) 

 has, however, adduced many arguments to show that the ordinarily received state- 

 ment above given should be reversed, and that the state of elongation should be re- 

 garded as the really active condition of muscular fibre, in which all its vital proper- 

 ties and peculiarities are most strongly marked, whilst the state of contraction is due 

 to its being left to the influence of the attractive forces inherent in its molecules, the 

 most energetic operation of which is seen in the rigor mortis. According to Lavdovsky 

 (Centralblatt, 1871, p. 769) the unstriated muscle fibres of Leeches and Worms, when 

 stimulated, first elongate and become attenuated, and then contract and become 

 thickened. The number of successive contractions that can be made to occur per 

 minute in isolated muscle-cells varies from 10-20, which is the ordinary number, to 

 36-40, which only happens in very lively animals. 



8 Harless, Abhand. Munch. Akad., 1862, p. 357. Luige Fasci, Virchow's Jahres- 

 bericht, 1867, p. 80. 



3 In rigor mortis, Pick, in Vierteljahrsch. der Naturf. Gesell. in Zurich, 1867, 

 with Dybkowsky, observed a rise of 0.05 0.07 C., and they attribute the rise in 

 temperature sometimes observed in bodies after death, to this source, the muscles 

 then becoming rapidly stiff. 



4 Reichert and Du Bois-Reymond's Archiv, 1863, p. 422. See also his work on 

 Tetanus, Leipzig, 1865. 



5 Weiss. Wien. Akad. Sitz-ber., Bd. Ixvi, p. 284. 



6 Muller's Archiv, 1845. 



