VOLUNTARY MUSCLES. 457 



rangement in this tissue is peculiar. From the smallest 

 arterioles, capillary vessels are given off, arranged in a net- 

 work with tolerably regular, oblong, rectangular meshes, 

 their long diameter following the direction of the fibres. 

 These envelop each primitive fasciculus, enclosing it com- 

 pletely, the artery and vein being on the same side. The ca- 

 pillaries are the smallest in the whole vascular system.. When 

 distended with blood they are from -^Yo" to 31 l $ Q of an inch 

 in diameter ; and when empty their diameter is from 70 1 0() 

 to -g-gVo f an inch. 1 



The arrangement of the lymphatics in the muscles has 

 never been definitely ascertained. There are numerous lym- 

 phatics surrounding the large vascular trunks of the extremi- 

 ties and of the abdominal and thoracic walls, which, it would 

 appear, must come from the substance of the muscles ; but 

 they have never been traced to their origin. Sappey has 

 succeeded in injecting lymphatics upon the surface of some 

 of the larger muscles, but never has been able to follow them 

 into the muscular substance. 3 



Connection of the Muscles with the Tendons. It is now 

 generally admitted that the primitive muscular fasciculi 

 terminate in little conical extremities, which are received 

 into corresponding depressions in the bundles of fibres com- 

 posing the tendons ; but this union is so close, that the muscle 

 or the tendon may be ruptured without a separation at the 

 point of juncture. In the penniform muscles this arrange- 

 ment is quite uniform and elegant. In other muscles it is 

 essentially the same, but the perimysium seems to be contin- 

 uous with the loose areolar tissue enveloping the correspond- 

 ing tendinous bundles. 



Chemical Composition of the Muscles. We are as yet so 

 little acquainted with the exact constitution of the nitrogen- 

 ized constituents of the body, that we cannot appreciate the 



1 KOLLIKER, Elements (Fhistologie humaine, Paris, 1868, p. 220. 



2 SAPPEY, Traite cTanatomie descriptive, Paris, 1868, tome ii., p. 27. 



