

STRUCTURE OF MUSCULAR TISSUE. 311 



to the non-striated form; but the two sometimes come into very close apposition, 

 as where the constrictors of the pharynx overlie the muscular coat of the oaso- 

 phagus itself. 1 



307. The Chemical Composition of Muscular Fibre seems to be very' uniform, 

 from whatever source it is obtained. It is impossible, however, to determine it 

 with precision ; on account of the difficulty of completely isolating the substance 

 of the fibres from the areolar tissue, vessels, and nerves, that are blended with 

 them. The proper muscular substance differs from the simple fibrous tissues, 

 in not being resolvable into gelatin by the prolonged action of boiling water ; 

 and in being soluble in acetic acid, from which it is precipitated by ferrocyanide 

 of potassium, showing that it belongs to the proteine-compounds. It is not, 

 however, true Fibrin, but corresponds rather to coagulated Albumen ( 21, 

 25). The following analysis of Muscle by Berzelius corresponds very exactly 

 with those since made by Braconnet, Schultz, Marchand, and other chemists : 



Proper Muscular substance . . ., ; . 



Gelatin (from areolar tissues) . . 



Albumen and haematin . 



Phosphate of lime, with albumen 



Alcoholic extract, with salts (lactates ?) 



Watery extract, with salts 



Water, and loss .... 



15.80 

 1.90 

 2.20 

 .08 

 1.80 

 1.05 



77.17 



100.00 



Thus something less than 23 per. cent of solid matter exists in ordinary meat; 

 and in 100 parts of this solid matter, there are about 3? parts of fixed salts. 

 The close correspondence in ultimate composition, between dried Muscle, and 

 dried Blood, according to the analyses of Playfair and Bb'ckmann, is not a little 

 remarkable. The following are their results : 



PLAYFAIR. BOCKMANN. 



Muscle. Blood. Muscle. Blood. 



Carbon 51.83 51.95 51.89 51.96 



Hydrogen 

 Nitrogen 

 Oxygen 

 Ashes 



7.57 7.17 7.59 7.33 



15.01 15.07 15.05 15.08 



21.36 21.39 21.24 21.21 



4.23 4.42 4.23 4.42 



The nature of the saline constituents of Muscle, however, indicates its relation 

 to be rather with the contents of the Corpuscles, than with the Blood as a whole 

 ( 140); for the percentage composition of the entire Ash is chloride of po- 

 tassium 14.8, phosphoric acid 36.6, sulphuric acid 2.9, potash 40.2, and earths 

 with oxide of iron 5.6. Some very interesting researches have been made by 

 Helmholtz, 2 on the chemical changes induced in the tissue by Muscular action. 

 Powerful contractions were induced by electricity in the amputated leg of a Frog, 

 and were kept up as long as the irritability was retained : the flesh of the two 

 limbs was then analyzed; and it was found that, in every instance, the water- 

 extractive was diminished in the electrized muscle, to the extent of from 20 to 

 24 per cent., whilst the alcoholic extract was increased to about the same amount. 

 Similar results were obtained from experiments on warm-blooded animals ; the 

 amount of change, however, being less, on account of the shorter duration of 

 their muscular irritability. It may be expected that more exact analyses will 



1 The distinctness of the two kinds of tissue is curiously marked in the case of the 

 parasitic Trichina spiralis, which infests the striated-fibre muscles alone, and may be seen 

 to stop short at the margin of the inferior constrictor, without passing on to the tissue 

 beneath. 



2 "Miiller's Archiv.," 1845. 



