274 MUSCLE-TISSUE. 



Blood-vessels are very numerous in striped muscles. They 

 are seen running in the external perimysium as larger arteries 

 and veins, and when reaching the surface of the bundle they 

 ramify into capillaries, which are found in the internal perimy- 

 sium without entering the muscle-fiber itself. All vascular for- 

 mations of the striped muscle are characterized by very marked 

 bifurcations at right angles, and this is especially a prominent 

 feature of the branches of the arterioles and the first capillaries 

 arising from them. (See Fig. 117.) 



Lymph-vessels are also numerous formations in the tissue of 

 the striped muscle, and, as regular injections show, they always 

 form a closed system of capillaries, which accompany the arterial 

 and venous blood-vessels. 



THE STRUCTURE OF THE MUSCLE OF THE LOBSTER. 

 BY M. L. HOLBROOK, M. D.* 



When we read the history of those scientific investigations which have been 

 made by our most excellent observers during the last forty years, we can 

 hardly fail to be convinced that even the simplest facts of natural philosophy 

 are only established after long-continued and patient research. Truth is 

 rarely or never reached in a straight line, but only by a tortuous and zigzag 

 course. At times we seem to have it almost within our grasp, and then it 

 becomes lost to view, and we are compelled to seek for it in a new direction. 

 All this is true when applied to the research of muscular structure, as we 

 shall see. 



The muscular system, as we know, constitutes the motor apparatus of all 

 complex animal bodies. By it all movement from place to place, all change 

 of shape and form, are accomplished. All motions of the body are based upon 

 the contraction of the two Varieties of muscle-fibers, for they possess in the 

 highest degree the same property seen in every portion of living matter, in 

 every simple organism, in every plastid the power to contract. From this 

 it is fair to conclude that muscle must also be living matter. 



Our modern views on the structure of striated muscle date back as far as 

 the year 1839, when Th. Schwann,t in his celebrated researches on the iden- 

 tity of the structure of the animal and plant, maintained that the striated 

 muscle is composed, of- innumerable, extremely delicate fibrillae, of a beaded 

 or rosary-like appearance. A number of such fibrillse, the beads of which 

 stand in one line close together, would, according to his view, form a 

 muscle bundle. If we look at a muscle-fiber, we notice alternating light and 

 dark lines of a definite width, and these, according to Schwann's view, 

 originated in the regularity in which the thick and thin portions of the 

 fibrillse are placed side by side. 



W. Bowman t demonstrated that the fibers sometimes break up, when sub- 



* Printed from the author's manuscript. 



t " Uutersuchungen iiber die Uebereinstimmung," etc. Berlin, 1839. 



t Todtl's Cyclopedia, 184P. 



