A 



[351 ] 



LXIII. Note regarding the Structure of Muscle, 

 By Martin Barry, M.D., F.R.SS. L. and E.* 

 TN Part I. of the Philosophical Transactions for the present 

 ~ year (p. 99) I mentioned having often seen a muscular 

 fibril becoming a fasciculus ; and gave delineations of fibrils 

 undergoing this change. I happen to have just made a pre- 

 paration in which the transition is remarkably well seen, and 

 have sketched it (chiefly in outline) in the accompanying figure. 

 At A, the young fasciculus still exhibits the double spiral ; 

 while at B, it is so far advanced as to present the usual trans- 

 verse striae. Here the striae are too minute for examination. 

 The preparation is from muscle of a fish. In the fasciculus 

 C (from the Turtle), the 



transverse striae are obviously /*"?» 



produced by the windings of 

 spiral threads. D represents 

 an enlarged fibril or young 

 fasciculus, varying in its ap- 

 pearance at different parts 

 from being twisted on itself. 

 The preparations themselves 

 are in a state in which they 

 may be viewed by my friends. 



It is a striking fact, that 

 the conversion of the fibril 

 into the fasciculus is more 

 frequently met with in the 

 ever-acting heart, than in any 

 other part that I have exami- 

 ned. The heart of the Turtle 



is that which I usually em- r"" \ 



ploy and recommend. The 



muscle may be preserved in very dilute spirit, a drop of which 

 is preferable to water as a medium for the examination. It 

 will be found advantageous to freeze the muscle, as then it is 

 possible, by means of a razor, drawn in the direction of the 

 fibres, to slice off an exceedingly thin lamina, which being 

 thawed, a narrow strip of it should be detached and teased out 

 with needles. , 



Fibrils are reproduced and. multiplied by means of nuclei, 

 which in certain states present the appearance of rows of bead- 

 like particles. These, — the mere elements of spirals, — seem 

 to be what some observers have supposed to represent the 

 structure of the formed fibril. 



* Communicated by the Author. 



k 



IB 



