On the Minute Structure of Striped Muscle, fyc. 287 



" On the Minute Structure of Striped Muscle, with Special 

 Reference to a New Method of Investigation, by means of 

 ' Impressions ' stamped in Collodion." By JOHN BERRY 

 HAYORAFT. M.D., D.Sc., F.R.S.E. Communicated by Dr. 

 KLEIN, F.R.S. (From the Physiological Laboratory, Univ. 

 Edin.) Received January 2, Read January 8, 18yl. 



[PLATE 6.] 



Historical. 



Curiously enough many of the early microscopists Schwann for 

 instance recognised that the fibrils of a muscle are not simply 

 threads of uniform thickness, like those of connective tissue : they 

 were able to demonstrate their varicose character, even with the 

 imperfect lenses ac their command. They concluded of course 

 without any experimental proof that the cross striping of the 

 fibrils, and, therefore, of the fibres themselves, was an optical expres- 

 sion of such varicosity. 



But Bowman, while believing apparently that the striping was 

 optical, and comparing the muscle fibril to a beaded rod of glass, 

 succeeded in breaking up the fibrils into little segments. 



According to his view, these " sarcous elements," as he termed 

 them, joined end to end by cement, constituted a muscle fibril. He 

 further believed that each sarcous element coincided in position with 

 one of the alternating stripes, the other kind of stripe corresponding 

 with the position of the cement joining the segments together. 



But no sooner had histologists begun to associate the cross-striping 

 with structural differences along the fibrils, than their varicosity was 

 almost entirely lost sight of, and every new stripe (and many were 

 discovered by Dobie, Hensen, and others) was gratuitously assumed 

 to mark the position of some new structure. 



There was, however, much to excuse what might at first sight 

 appear to have been a great want of critical acumen, for the applica- 

 tion of staining reagents appeared to bring out alternating differences 

 of structure along the fibre. Thus, with logwood or picrocarmine or 

 eosine, the clear stripe (isotropic bands), the dark stripe (Querscheibe; 

 disque epais), the band of Hensen (Mittelscheibe ; disque median), 

 and Dobie's line (Querwand ; strie mince), all appear to take on the 

 stain in different degrees, so much so that, in specimens successfully 

 prepared, some stripes appear deeply stained, others hardly at all. 



Then, again, Brllcke and other investigators demonstrated that the 

 fibrils consist of alternating parts, some of which appear to be doubly, 

 and others singly, refracting. 



Overwhelmed by what appeared to be such a mass of evidence, the 



