STRUCTURE OF THE HUMAN BODY. 49 



muscles appear coarse or fine according to the size of these 

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25. frhese fibres appear to be very uniform as to shape, 

 size, and general appearance, being delicate, soft, flattened, 

 and though consisting only of a tender pulp, still solid,/ (The 

 fibrous and fascicular arrangement appears to be chiefly con- 

 fined to muscles of voluntary action, as they are scarcely 

 perceptible in the heart, and not at all in the alimentary 

 canal, or urinary bladderjl In the stomachs of birds, how- 

 ever, the fibrous structure is very distinct, especially in 

 hawks and owls. 



The appearance of the ultimate fibres and of their transverse lines, as 

 seen under the microscope of Mr. Lister, when the object is magnified 



500 diameters. 



26. The muscular fibres are every where penetrated by 

 cellular tissue and numerous blood-vessels and nerves. /The 

 colour of the muscle of course varies, according to the quan- 

 tity and quality of the blood.) In adult animals it is of various 

 shades of red ; in young animals, of a cream colour, as in 

 veal ; in birds, it varies in different muscles ; in fowls, for 

 example, it is white, on the breast, and a deep brown on the 

 legs ; whilefin fishes, it is bluish, or white,)&c. 



27. No part of the body except, perhaps, the organs of 

 sense, is so abundantly supplied with blood-vessels and 



6 



