MUSCLE-TISSUE. 



269 



structure is extremely simple, and proved to be so by the 

 description of E. Briicke, in 1857 (see page 127). The only addi- 

 tion I have to make is that all sarcous elements, whatever may 

 be their size and arrangement, are uninterruptedly connected in 

 both longitudinal and transverse directions. The division of 

 the muscle-fiber into the longitudinal fibrillas of Schwann 

 depends upon a very close aggregation of the sarcous elements 

 in a longitudinal direction. The beaded appearance of these 

 fibrillaa can be explained only by the presence of filaments, con- 

 necting the sarcous elements 

 in a lengthwise direction. 

 Muscles kept in alcohol ex- 

 hibit this characteristic very p. 

 distinctly. If, on the con- 

 trary, sarcous elements are 

 aggregated more closely in 

 transverse direction, either 

 after mechanical injuries, by 

 teasing, or after the applica- 

 tion of certain re-agents, 

 such as dilute muriatic, 

 nitric, lactic acid, or the 

 stomachic juice, Bowman's 

 disks will be the result. 



The smaller the sarcous 

 elements in a muscle-fiber 

 are, the more rapid and con- 

 tinuous the action of the mus- FlG us. ATTACHMENT OF MUSCLE- 

 cle, and vice versd. The heart, FIBERS TO PERIOSTEUM. FROM THE 

 being the most active of all SCAPULA OF A CAT. CHROMIC ACID 

 muscles, has the smallest sar- SPECIMEN. 



C011S plpTYlPTlt^ TllP blower M ' P inted end of muscle-fiber; S, the sarco- 



lemma, closely attached to the perimysium, P, 



ail ailimal in its motions, the which blends with the fibrous connective tissue of 

 ., T periosteum. Magnified 500 diameters. 



larger are its sarcous ele- p 



ments. In accordance with what I said on the structure of bio- 

 plasson in general, it will be readily understood that contracti- 

 bility is increased with the smallness of the points of intersection 

 of the reticulum. Normal, fresh muscle-fibers sometimes exhibit 

 very small and irregularly distributed sarcous elements and 

 active contractions under the microscope. Muscles of the craw- 

 fish, the lobster, and the water-beetle are, on account of the large 

 size of their sarcous elements, excellent objects for study. As 



