204 THE MICROSCOPE. [October, 



The Ultimate Structure of Striated Muscle.* 



By. J. H. WYTHE, 



OAKLAND, CAL. 



The errors of interpretation are not uncommon in any branch 

 of science, and need to be specially guarded against in histology, 

 since many structures are not only complex in their living state 

 but are liable to change after death. While post-7Jiortem appear- 

 ances may indicate living diversities, they may also indicate 

 physical and chemical alterations. The various reagents used 

 to differentiate structure may also produce appearances very 

 different from the living state, while the most perfect objectives 

 will only allow one to see accurately that part of the object which 

 lies in the optical plane. These sources of difficulty, in addition 

 to diffraction lines and ghostly images produced by imperfect 

 illumination, render the task of investigating minute structure by 

 no means easy, yet care in the preparation and observation of 

 structure, and comparison with the recorded views of others, will 

 surely lead one in the right direction. 



The structure of striated muscle fibre has been a vexed question 

 since the beginning of microscopic investigation, although many 

 text-books, so called, flippantly describe it and many other imper- 

 fectly known structures as matters of positive knowledge. Such 

 descriptions hinder the progress of true science. On the other 

 hand, it is necessary to avoid the opposite sentiment of impracti- 

 cability. Doctor Dallinger, the able editor of the last edition of 

 " Carpenter on the Microscope," declares that "it is well in the 

 present state of knowledge to refrain from conclusions as to the 

 absolute structure of the striated fibrillse. It ranges itself, from 

 the modern microscopist's point of view, with other striated 

 objects, and will require the possession of lenses of a numerical 

 aperture twice or thrice those which are now within our reach." 

 Such an assertion from so eminent a source is extremely unfortu- 

 nate. Its tendency can only be to discourage and abridge micro- 

 scopical pursuits. If this spirit had prevailed in former times 

 few discoveries in histology would have been reported. 



Soon after the microscope was applied to the investigation of 

 tissues it was found that the fasciculi, or fleshy bundles of volun- 

 tary muscle, were separable into fibres, which were divisible 

 into minuter fibres, or fibrillae. Under some circumstances, such 

 as treatment with dilute hydrochloric acid, the fibres showed a 

 tendency to divide into discs. With a magnifying power of 250 

 diameters, or more, the fibres also showed alternate light and 

 dark spaces, the origin of which has given rise to much discussion. 



Bowman, Virchow, and others describe the fibre as consisting 

 of bead-like granules, lying side by side, and the fibrillar or discs 



*Read before the San Francisco Microscopical Society, July 6, 1892. 



