OENEEAL CONSIDERATIONS ON TEE STRIPED MUSCLES. 



235 



Fig. 151. 



with the length of its fibres ; for the latter alone give an indication of the possible 

 degree of shortening it is capable of — this shortening being estimated at one- 

 fourth the length of its contractile fibres. In glancing at the different an'ange- 

 ments shown in Fig. 152, it will be seen that, with muscles which have the same 

 total length, that of the contractile elements varies within extensive limits. 



C. Vessels and Nerves. — The muscular 

 tissue receives much blood ; the fibrous tissue 

 very little. The arteries are large and numerous, 

 and each is accompanied by two veins. The 

 capillary vessels anastomose in such a manner 

 as to form rectangular meshes, the greatest 

 diameter of which is directed towards the length 

 of the muscle. 



Ranvier has remarked that, in the dark 

 muscles of the Rabbit, the vascular network has 

 varicose formations which retain a considerable 

 mass of blood in the interior of the muscles. 



The lymphatic vessels of the muscles are 

 few ; they sometimes penetrate their interior in 

 following the capillaries ; at other times they 

 remain on the sm-face, in the external perimy- 

 sium. The existence of lymphatics has not yet 

 been demonstrated in tendons, aponeuroses, or 

 synovial membranes. 



The nerves emanate from the cerebro-spinal 

 centre. At their tenninal extremity they offer 

 a small enlargement, called by Rouget the motor 

 end plate, and by Doyere and Kiihne the nervous 

 colline (hillock). It is admitted that the motor 

 tube traverses the sarcolemma, there losing its 

 envelope ; and that the substance of the axis- 

 cylinder is spread over the surface of the muscular fibrillae to form the motor 

 plate. 



Physico-chemical Properties of Striped Muscles. 



Muscles are soft organs, remarkable for their more or less deep-red colour, 

 which varies with the species, and even with the age and health of animals of the 

 same species. 



By desiccation, muscles become hard and brown ; by repeated washing they 

 assume a straw-yellow tint. 



Muscles are extensible, elastic, and tenacious ; and their tenacity is more 

 marked during life than after death. 



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

 marked acid reaction when extracted from a muscle which has been actively con- 

 tracting. (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, " myosin," 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, creatinine, and a somewhat large proportion 

 of sarco-lactic acid. The solid substance of the muscle may be partly transformed 



TRANSVERSE SECTION OF FROZEN MUS- 

 CLE, MAGNIFIED 400 DIAMETERS. 



N, Nerve. M, Muscular fibre, sur- 

 rounded by portions of six others : 

 a, nucleus of the nerve-sheath ; 

 6, nucleus of the sarcolemma ; c, 

 section of nucleus of terminal plate 

 of nerve ; cf, transverse section of 

 terminal plate, surrounded by gran- 

 ular material; e, transverse section 

 of muscle nuclei ; /, fine fat-drops. 

 The angular dark particles are sec- 

 tions of sarcous elements ; the clear 

 intervening spaces represent the 

 fluid isotropal part of the muscle 

 substance. 



