1881.] 



the Striation of Voluntary Muscular Tissue. 



361 



portant and brilliant contributions to the literature of this subject, 

 and taking him as a landmark, it is convenient to speak of investi- 

 gators before or after his time. Among the former Schwann, quoted 

 by Miiller ("Physiology," translation by Baly, vol. ii, p. 878), describes 

 the striated voluntary fibre, indicating its shape and size. The cross 

 markings were observed by him, and, indeed, with one or two 

 remarkable exceptions, by all the early observers (Lauth and Wagner, 

 in Muller's " Archiv fur Anatomie und Physiologie, und Wissenschaft- 

 liche Medicin," pp. 4 and 318, of the year 1835). Schwann, with 

 Bauer, Krause, Miiller, Home, Valentin, and Milne Edwards recog- 

 nised the important fact that each fibre is composed of a number of 

 threads or fibrillae, packed side by side and joined together by a 

 transparent tenacious fluid (Krause), and, moreover, that these 

 threads or fibrillae are cross striated, as is the fibre itself. Although 

 Schultze describes the fibrillae as being uniform filaments, he is alone 

 in this opinion, most of his contemporaries recognising the beaded 

 appearance.* The beaded thread was the cause of some dispute, for 

 the question arose, was it a linear series of globules or a moniliform 

 filament ? and the final settlement of this must, indeed, have been 

 a matter of great difficulty to those older savants, when we consider 

 tbe imperfect lenses at their disposal. Krause and others maintained 

 the former view, while Schwann held that which subsequent investi- 

 gators have shown to be the correct one. The fibrillse, according to 

 Schwann, present a very regular succession of bead-like enlargements, 

 darker than the very short constrictions which lie between. Thus, 

 before the time of Mr. Bowman, the following important facts had been 

 made out, namely, that the fibre is composed of a bundle of beaded 

 fibrillae cemented together, and that the fibrillae are cross striped, giving 

 the whole fibre a like appearance of striation. Erroneous views had 

 often, it is true, been advanced, but these had never received general 

 acknowledgment. Mr. Skey (" Phil. Trans.," 1837), for instance, 

 considered the fibres to be tubes filled with a soluble gluten, the stria? 

 surrounding and binding them together. Leeuwenhoek had a some- 

 what similar view of the construction of the cross striae, and Prochaska 

 considered them as depressions caused by the clasping of neighbouring 

 capillaries and thready tissues. 



Mr. Bowman communicated to the Royal Society, in 1840, a 

 paper " On the Structure and Movements of Voluntary Muscle," in 

 which he confirmed many of the opinions of his predecessors, adding, 

 at the same time, much of what was fresh to our store of knowledge. 

 He it was who first described the thin elastic membrane (sarcolemma) 

 covering and ensheathing the fibres, showing how easily to demon- 



* Consult a drawing by Allen Thomson in illustration of Dr. Martin Barry's 

 paper on the structure of muscular fibrils, "Phil. Mag.," series 4, vol. 5, Plate Y, 

 fig. 2. 



2 d 2 



