116 STUDIES IN ADVANCED PHYSIOLOGY. 



posed of alternating light and dark disks, somewhat like a 

 stack of coin might be composed of alternate copper cents 

 and silver dimes. If a crushed portion of a fibre be exam- 

 ined it is possible to make out a delicate covering extend- 

 ing entirely around the fibre, known as the sarcolemma. In 

 this sarcolemma lie the more or less semi-liquid contents, 

 which exhibit the striation referred to. 



Nuclei. Scattered along the fibre here and there, and 

 lying immediately underneath the sarcolemma, are nuclei. 



Measurements of an Individital Fibre. Measurements 

 of these fibres in an adult muscle give a length of from one- 

 half inch to an inch and a half, and a width of about one 

 five-hundredth of an inch. L,ittle floating gossamer threads 

 cut in lengths of an inch or more may serve to give us an 

 idea of their actual size. It will be seen from their length 

 that an individual muscle fibre does not run the entire 

 length of a muscle, as many muscles are five, six, or more 

 inches in length. 



Attachment to Tendons. A delicate fibril from the ten- 

 don may be traced to the end of a muscle fibre where it is 

 directly cemented to the sarcolemma. An older view that 

 the tendons are but the connective tissue of a muscle 

 extended, is no longer tenable. Whether such tendon 

 fibrils run to both ends of all fibres, is still a matter of 

 question. Some histologists claim two or more muscle fibres 

 may be cemented end to end; others again that the muscle 

 fibres are twisted and intertwined with each other some- 

 what like threads in a rope, and that tendons attach them- 

 selves merely to the outermost fibres. The probability of 

 the matter, however, is that in the majority if not in all 

 cases each individual fibre receives at both of its ends a 

 delicate little fibril from the tendon, which fibril is directly 

 and firmly cemented to its sarcolemma. This would make 

 each individual muscle fibre in reality a separate muscle. 



Blood Supply. A voluntary muscle is quite vascular, 

 each fibre being invested with a capillary net-work almost 



