56 



GENERAL ANATOMY. 



a substance called syntonin, nearly identical with the fibrine of the blood ; but, 

 unlike the latter, not dissolved by nitrate of potash. Muscle after death ex- 

 hibits an acid reaction ; but this appears to be due to post-mortem changes. 



Fig. 24. 



Fig. 25. 



Non-striated elementary fibres from the human 

 colon, a. Treated with acetic acid, showing the 

 corpuscles, b. Fragment of a detached fibre, 

 not touched with acid. 



Muscular fibre cells from human arteries. 1. From 

 the popliteal artery : a, without ; b, with acetic acid. 

 2. From a branch of the anterior tibial : a, nuclei of 

 the fibres. (Magnified 350 times.) 



The capillaries of muscle are very abundant, and form a series of rectangular 

 areolae, the branches, which run longitudinally between the muscular fibres, 

 being united at short intervals by transverse anastomosing branches. 



Nerves are profusely distributed to the muscular tissue, more especially to 

 the voluntary muscles. The mode of their termination will be described on a 

 subsequent page. 



The distribution and the mode of origin of the lymphatic vessels of muscle 

 has not yet been ascertained. 



The muscles during life, and for some time after death, respond to the appro- 

 priate stimulus by contracting in the manner peculiar to the class to which they 

 belong. Thus, for some time after a limb has been amputated, its muscles can 

 be set in motion by scratching, pinching, or galvanizing them ; and even after 

 the irritability of the muscular tissue has been exhausted by the prolonged 

 suspension of the circulation, it can be at first temporarily restored by injecting 

 fresh arterial blood through it (Brown-Se'quard). The time at which muscular 

 irritability ceases after death depends on the vitality of the subject; thus it 

 ceases in birds, whose circulation and vital heat are of a very high degree, 

 sooner than in man and quadrupeds ; in these sooner than in fishes, &c. Dr. 

 Sharpey says that it lasts long in hybernating animals killed during their 

 winter sleep. It is also affected by the mode of dying, being extinguished in- 

 stantaneously (as is asserted) in some cases of lightning-stroke, and much di- 

 minished by certain gaseous poisons, particularly sulphuretted hydrogen. 



As the muscles die they become stiff, and it is to this cause that the rigidity 

 so characteristic of recent death (" rigor mortis") is due. The ultimate cause 

 of the phenomenon is not well understood, beyond the obvious fact that it must 

 be due to the change from partial fluidity to a solid condition of the contents 

 of the sarcolemma. The periods of its occurrence and of its disappearance are 

 very variable, and the causes of those variations are of extreme interest and 

 importance, especially in medico-legal inquiries, but the subject is too compli- 



