MUSCULAR FASCICULI AND FIBRILS. 



433 



Fig. 211. 



hibit the characteristic appearance 

 of transverse striation, as in the 



Fig. 212. 



Striated muscular fasciculi, magnified K5 diameters. 



Sarcolemma of fish. 



photograph of muscular structure of the frog (Fig. 211). voluntary mus- 

 The primary fasciculi are collected into larger bundles, cuiar fasciculi. 

 secondary muscular fasciculi, held together by connective tissue, and 

 these, again, into still larger, the tertiary. 



The primitive fasciculus is enveloped in a delicate sheath, the sarco- 

 lemma, as shown in. Fig. 212, in which the fasciculus, though torn across, 

 is held together by the sarcolemma. The specimen is from the human 

 muscle. Fig. 213 is a good representation of the same fact. It is given 

 by Todd and Bowman from the skate. The sarcolemma is a delicate 

 membrane, which, though of great tenuity in man, may be made visible 

 by the action of acetic acid or alkalies. Within the sarcolemma the 

 primitive fasciculus is seen to be composed of many parallel fibrils, 

 which may, by maceration or chemical agents, be separated from one an- 

 other. These fibrils present a beaded aspect, and, since their constituent 

 elements are arranged side by side in parallel planes, they ultimate mus- 

 give to the fasciculus the appearance of striation it presents. cular fibril - 



The longitudinal striation of the fas- 

 ciculus arises from the fibrils them- 

 selves. Here and there, in the inte- 

 rior of the sarcolemma, nuclei occur ir- 

 regularly, and with them fat granules. 

 The fibrils, with the fat and a liquid, 

 fill the sarcolemma, without leaving 

 any central canal or hollow axis. 



Fig. 214 is a photograph of ulti- 

 mate muscular fibre of the pig, from 

 one of Mr.Lealand's preparations. The 

 rectangular form of the constituent 



Ultimate muscuuTfi^HI^d 200 diameters. Cells IS Well Seen at 0, a, a. At , 



EE 



- 214 - 



