820 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



or five seconds, and slowly disappearing. A further phenomenon has beeu 

 noticed in the same muscles by Auerbach 1 after an energetic blow ; namely, 

 a wave or undulating contraction, proceeding from either side of the local 

 intumescence of Schiff, and propagating itself to the extremity of the muscle 

 at the rate of about eighteen inches per second. The breadth of the waves 

 is about a quarter of an inch at their base, and they gradually die out as 

 they spread from the point struck. It is doubtful whether both of these 

 appearances are not due simply to a prolonged contraction of the muscle, 

 resulting from exhaustion of its contractility at the excited spot. 



669. Sudden variations of temperature induce persistent contraction of 

 muscular tissue; thus the legs of a frog, dipped into water at a temperature 

 either as high as 130 or as low as 25 Fahr., become tetanized. V. Bezold 2 

 and Prevost have found that in a certain stage of Veratrin poisoning the 

 muscles respond to a single electric shock, not with a single short contraction, 

 but with a persistent tetanic contraction ; and, according to AVeyland, the 

 same results from the action of Sabadillin, Delphiuin, Emetin, and Acouitin. 3 

 As regards chemical agents, some appear to act with equal energy in pro- 

 ducing contraction, whether applied to the muscle or to the motor nerve, as 

 solutions of potash and soda; others, as creosote, alcohol, pure lactic acid, 

 and glycerin, act on the muscle through the nerve, but possess little stimu- 

 lating power when directly applied to the muscle ; and others again excite 

 energetic contraction when made to act immediately on the muscle, but 

 scarcely operate through the nerve, as sulphate of copper and ammonia. 4 

 Ktihne 5 remarks that all those bodies which coagulate the muscle plasma, 

 as dilute acids and alkalies, act as powerful stimulants to muscles even when 

 very dilute. The metallic salts, as a rule, require to be in a stronger state 

 of concentration. He thinks that each part as it contracts, generates material 

 (paralactic acid) which again acts as an excitor to the next adjoining layer. 



670. Muscular Irritability is deadened by many substances, and especially 

 by those which have a narcotic or sedative action on the nervous system. 

 In carbonic acid gas, hydrogen, carbonic oxide, or sulphurous acid gas, 

 muscles contract very feebly, or not at all, when stimulated ; whilst in 

 oxygen they retain their irritability longer than usual. Narcotic substances, 

 such as a watery solution of opium, when applied directly to the muscles, have 

 an immediate and powerful effect in diminishing or even destroying their 

 irritability ; this effect is also produced, though in a less powerful degree, by 

 injecting these substances into the blood. In the same manner venous blood 

 charged with carbonic acid, and deficient in oxygen, has the effect of a poison 

 upon the muscles, diminishing their irritability, when it continues to circulate 

 through them, to such a degree that they sometimes lose it almost as soon as 

 the circulation ceases, as is seen in those who have died from gradual and 

 therefore prolonged asphyxia. The unfavorable influence of venous blood 

 is also shown in the Morbus Coeruleus, patients affected with which are in- 

 capable of any considerable muscular exertion. Although most of the 

 stimuli which occasion the contraction of muscles, when directly applied to 

 their fibres, operate also when applied to their motor nerves, the same does 

 not hold good in regard to those agents which diminish irritability. It is a 



1 Abluind. dn- Schloswig. Gesellsch., 1861, p. 294. 



2 CentralblaU, 1809, p. (H)O. 



3 Sec I'ur an extensive series of researches on this point, including the action of 

 Tartar Kinetic, Upas Antiar, Cuffein, Chloroform, Napellin, Quinine, and other 

 drugs, Buchlieim and Eisenmenger in Eckhard's Beitrage zur Anat. u. Physiol., 

 Bd. v, 1871, p. 73. 



4 Sec Dr. Duflin's paper, On Muscular Contraction, in Beale's Archives of Medi- 

 cine, vol. iii, p. 147; and Kiihne in Archiv f. Anat. und Physiologic, 1859, p. 213. 



6 Physiul. Chcmie, 1868, p. 311. 



