On the structure of cross-striated muscle. 179 



representations, does not detract from the substantial accuracy of the 

 statement with which this paragraph commences. 



Although that statement refers more especially to the ordinary 

 cross-striated muscles, such as those which form the skeletal muscles 

 of Vertebrates and the muscles which move the legs and body seg- 

 ments of Arthropods, it is none the less true for the remarkable 

 variety of cross-striated fibre which serves to move the wings of most 

 insects. The descriptions and representations, which are given by all 

 recent authors, of the appearances of these fibres, which for the sake 

 of brevity I shall in future refer to as the wing-muscles, are practi- 

 cally identical, and these appearances, it may also therefore be af- 

 firmed, are so far ascertained. Although in the case of most tis- 

 sues and organs it is not difficult, if the microscopical appearances 

 are distinct and are admitted by all who have given special attention 

 to the subject, for a general consensus of opinion as to the actual 

 intimate structure of the tissue to be arrived at, such consensus has 

 been remarkably lacking jn the case of cross-striated muscle. Quot 

 homines, tot sententiae might indeed be taken as the motto of any 

 article dealing critically with this subject. Nevertheless a tendency 

 has been manifested within recent years for those who have investi- 

 gated the question to become arrayed into two principal camps. Those 

 which occupy the one camp (A) are indeed fewer in number, but since 

 they include the names of Kölliker, Rollett and Ranvier, they must be 

 admitted to form a very powerful combination; the other camp (B) 

 includes by far the larger number of recent investigators, amongst 

 whom may be mentioned more particularly Melland, C. F. Marshall, 

 Carnoy, van Gehuchten and Ramon y Cajal. The fundamental idea 

 of those investigators who occupy what I have termed camp A is the 

 notion, (which must be eventually referred back to Schwann) that a 

 muscular fibre is essentially composed of longitudinal elements (fibrils 

 and muscle-columns, or groups of fibrils) which are continuous from end 

 to end of the fibre, and which are united into the fibre by interstitial 

 substance. The arrangement of this interstitial substance, in conjunc- 

 tion with the form and structure of the fibrils and muscle-columns, is 

 the cause of the appearances of transverse and longitudinal striation 



12* 



