OMNERAL ClWtUDKltA \ TIIK STItll'KIt MIWU-X. 181 



By desiccation, mnsclcs become hard and brown ; by rei>eated washing 



they assume a straw-yellow tint. 



Muscles an- extensible and elastic; they are also tenacious, and their 

 tenacity is inure marked during lii'e than after death. 



It has been remarked that the juice impregnating the muscular tissue is 

 distinguished from the serum of the blood by an acid reaction. (The fluid or 

 " muscle plasma " obtained by pressing flesh, is either neutral or slightly 

 alkaline. It soon coagulates and separates into two portions a semi-solid 

 portion, "myosiu," and the fluid serum that at ordinary temperatures quickly 

 acquires an acid reaction.) It holds in solution a variable quantity of 

 albumen, casein, fat, a little creatine, creatiuiue, and a somewhat large 

 proportion of lactic acid. The solid substance of the muscle may be partly 

 transformed into gelatine by boiling in water ; but its largest portion is a 

 nitrogenous substance, soluble in dilute hydrochloric acid, called " syutonine," 

 or muscular fibrino ; it differs but little from the fibrine of the blood. 



PHYSIOLOGICAL PBOPEBTIE8 OF THE BTEIPED MUSCLES. 



In this paragraph will only be discussed the development of the muscles, 

 muscular contractility, and the part the muscles assume in locomotion. 



A. DEVELOPMENT OF THE MUSCLES. A muscle is derived from a mass of 

 embryonic cells. Each cell becomes considerably elongated, and its nucleus 

 becomes multiple, to constitute a muscular fibre. The membrane of the cell, 

 enormously developed, forms the sarcolemma, while the contents of the cell, 

 Incoming more dense, divide longitudinally and give rise to the contractile 

 lilirillae. Lastly, when the muscles are formed, they grow by the augmenta- 

 tion in length and thickness of the primary fasciculi or muscular fibres. 



B. MUSCULAR CONTRACTIBILITY. Muscles possess the property of con- 

 tracting under the influence of a natural or artificial stimulus. Musrnl-ii- 

 i-niit mi-til, n is the phenomenon resulting from the operation of this property. 

 Muscles in a state of contraction are the seat of physical and chemical 

 phenomena ; they change their form and consistency, and become the theatre 

 of a relatively abundant production of carbonic acid, creatiuiue, and iuosinie 

 acid. During contraction, it has been remarked that the muscular fibres 

 contract by increasing in volume, like an india-rubber tube left to itself after 

 being extended : the zig-zag doubling mentioned by Prevost and Dumas has 

 not been observed. 



But these physical and chemical modifications, important as they are in 



Fig. 100. 



MU8ci-i..\i: ni!i:i: IN A STATE OF CONTRACTION i\ mi GOTO; im taaoM 



Al'l-KoXIM ATKI>; Till: UKLAIHII ol Illi; IMiKi: 1VI;IAMI>; AM. 1111 

 I.I.MMA I:\IM.H IN Vl.>|. I.I- ci\ US >l l:IA< I.. 



a physiological point of view, cannot longer bo dwelt upon here. It is parti- 

 cularly important to speak of muscular contraction. 



A mn-cle tliat contracts becomes shortened ; its two extremities approach 

 each other if they are free : or one dru\\s near the other if the latt- r is fixed 



