THE MUSCULAR SYSTEM. 239 



enlargements. The large fibrils in the perennibranchiate 

 Amphibia [Sire//, Proteus, Menopoma), (fig. 89), are above all 

 others adapted for this investigation. In these animals, when 

 they have been preserved in spirit, the fibrils become isolated in 

 considerable numbers, and may be examined on all sides; it is 

 the same with the muscles of the thorax in Insects. 



Quite lately, Dr. Barry, has propounded the view that each 

 muscular fibril is constituted of two spirally convoluted filaments 

 running in the same direction. I have seen nothing of the kind, 

 and do not hesitate to describe the whole of Dr. Barry's exposi- 

 tion as nothing but a myth, and his figures as fantastical images. 



As regards the notion adopted by Bowman, Dobie, and others, 

 that the fibrils are constituted of still more minute particles 

 (sarcous elements), it may perhaps be stated, as the study of 

 development shows, that the fibrils do, in fact, at first appear to 

 consist of separate particles. But the question is, whether in 

 the adult such elementary particles continue to be evident, and 

 this, at present, I am inclined to deny. 



The nuclei of the muscular fibres, in man, are situated; as I 

 agree with Schwann in stating, only on the inner surface of the 

 sarcolemma, and not within the fibrils; that they are not 

 placed externally on the fasciculi, as was formerly stated by 

 Henle and Stadelmann, and more lately by Gerlach, is readily 

 perceived, when the muscles are treated with alkalies. Under 

 these circumstances the partially-swollen nuclei escape, to- 

 gether with the fibrils, in a state of solution, from the sheaths, 

 which remain behind, and before they are dissolved may be 

 easily examined in an isolated state. In many muscles, even 

 when there are no granules between the fibrils, larger or 

 smaller fatty molecules occur around the nuclei.] 1 



1 [With regard to the vexed question of the ultimate structure of striped muscle, 

 we question if any real improvements have heen made upon the description originally 

 given by Mr. Bowman ('Phil. Trans.,' 1840), viz. that it consists of minute, dark, 

 subangular particles, the " sarcous elements," imbedded in a more transparent con- 

 necting substance or matrix ; that neither discs nor fibrils can be said to exist in the 

 normal state, — the breaking up of the muscular bundle into either of these elements, 

 resulting simply from the manner in which the lines of greatest cohesion are disposed, 

 at the time when mechanical violence is applied to it. The assertion in the text that 

 the fresh muscle of Man and the Mammalia does not break up into discs, is decidedly 

 erroneous — as we have seen it occur repeatedly. 



Nor can we grant the invisibility of the discs in longitudinal sections of muscle : 



