58 



MUSCULAR TISSUE. 



a dark stripe, while Dobie's line crosses each light stripe. This 

 latter is regarded by Schafer as not an actual structure, but an 

 effect produced by the transmitted light. One authority, Hay- 

 croft, regards the striated appearance of muscle as a refractive 

 effect simply ; but the evidence of this is not convincing, and the 

 difference in reaction to stain ing-agents seems to prove that the 

 light and dark stripes of muscle-fibers are different structures. 



*Sarcoplasm. 



FIG. 50. Diagram of the struct- 

 ure of the fibrils of a striated 

 muscle-fiber ; the light spaces be- 

 tween the fibrils may represent 

 the sarcoplasin (Huber). 



Sarcoplasm. 

 Fibrils. 

 -Sarcolemma. 



FIG. 51. Transverse section through stri- 

 ated muscle-fibers of a rabbit (Bohm and 

 Davidoff). 1 and 3, from a muscle of the 

 lower extremity; 2, from a lingual muscle; 

 X900. In 2, Cohnheim's fields are distinct; 

 in 1, less clearly shown ; in 3, the muscle- 

 fibrils are more evenly distributed. 



Nuclei are to be seen under the sarcolemma of the muscular 

 tissue presenting the usual appearance of cell-nuclei, often with 

 spiral chromoplasm. 



Endomysium is the areolar tissue between the individual fibers, 

 which are bound together by connective tissue, perimysium, into 

 bundles, fasciculi; these in turn, united by the perimysium, con- 

 stitute what is commonly called a muscle, whose investment or 

 sheath is the epimysium. 



The muscles of insects are characterized by broad stripes whose 



