THE MUSCULAR SYSTEM. 227 



of a line ; in the retraJiens auricula', 0-006-0-015, the greater part 0-008- 

 0-01 of a line. In a male, their diameter in the 'pectoralis amounted 

 to 0'018-0-28 of a line, the greater nutiiber measuring 0-02-0-022 of 

 a line ; in the deltoid, 0-012-0-02-i for the largest, and for the smaller 

 O-OlG-0-02 of a line ; in the obliquus abdominis ezternus, 0-16-0-024 and 

 0-016-0-02 of a line; in the orbicularis oris, 0-008-0-016 and 0-01- 

 0-012 of a line; in the frontalis, O-OOG-0-014 and 0-008-0-01 of a line. 

 In a second individual, the pectoralis major contained fibres of 0-0068- 

 0-024, most of them 0-018-0-02 of a line; the pyramidalis, some of 

 0-01-0-028, the majority 0-02 of a line. 



With respect to the nature of the primitive fibrils, much still remains 

 to be cleared up. In general they must be regarded as solid ; and, in 

 fact, there is nothing to indicate the existence of a cavity in them. It 

 is fully ascertained that it is to them that the transverse striation of the 

 primitive fasciculus is due. It is still doubtful, however, whence the 

 appearance of transverse striation in the fibrils themselves arises ; 

 whether from their being spirally tu'isted (Arnold), from zigzag curva- 

 tures (Will), or from varicosities. All that I have seen leads me to 

 adopt the latter view, which is also that most generally entertained. I 

 do not deny that, in the examination of numerous fibrils, appearances 

 are occasionally met with, favorable to the other two views, and parti- 

 cularly to that of Will ; but it is much more usual to find simple nodular 

 enlargements. The large fibrils in the perennibranchiate Amphibia 

 [Siren, 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 exposition 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 ele- 

 ments), 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 con- 

 tinue 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 



