146 THE MUSCULAR TISSUE. 



of functions, and form the especial and active agent in 

 locomotion. 



Fibrin is the chemical element constituting the great 

 mass of muscle, and peculiarly adapted to contraction. 

 The chemical composition of muscle is thus given by Ber- 

 zelius : 



Water, TY.lf Alcohol, ext with salts, 1.80 



Fibrin, 15.80 Watery, . fV 1.05 



Albumen with color- Phosphate of lime with 



ing matter, 2.20 albumen, 0.08 



The different varieties of muscular contraction are those 

 of force or intensity, duration, velocity, and extent ; and 

 examples of each variety may be seen in the several mus- 

 cles of the human body. The most rapid movements, ac- 

 cording to Haller, are to be found in the muscles of the 

 voice, since the pronunciation of a single letter can be exe- 

 cuted in the 1-3000 part of a minute. 



From experiments on the bodies of executed crimi- 

 nals, Mr. Nysten found that the muscles lost their contrac- 

 tility in the following order first, the left ventricle of the 

 heart, next the intestinal canal in 45 or 55 minutes, the 

 urinary bladder in nearly the same time; in one hour the 

 right ventricle, in one hour and a half the oesophagus, the 

 voluntary muscles a little later, and the last of all, the au- 

 ricles of the heart, particularly the right, which, it is said, 

 Tinder the influence of galvanism, contracted 16J hours after 

 death. Muscles also have sensibility, and are further en- 

 dowed with an especial sense, called the muscular sense, by 

 which the precise state of the muscles is made known. 



The development of the muscular system takes place from 

 the germinal membrane, which is made to consist of three 

 layers, an external or serous, an internal or mucous, and 

 a middle or vascular. The voluntary muscles or those of 

 animal life, found in the trunk and limbs, are developed 

 from the serous layer, while the involuntary or those of 

 organic life, comprising the intestines, bladder and inter- 

 nal organs of generation, are developed from the mucous. 



