MUSCLE. 



511 



tad inal" (doubly-spiral, flat,) " filaments are con- 

 tained and have their origin." 



This description, so entirely opposed to the 

 more simple view above given (and which was 

 already in type when the paper " On Fibre" 

 was read) demands a brief notice. The paper 

 of which it forms part, might perhaps have 

 been more explicitly entitled, " On the double 

 spiral structure of the organic world;' 7 for, 

 in it, the doubly-spiral flat filament, giving the 

 appearance of transverse striae to voluntary 

 muscle, is discovered to exist in the interior 

 of the blood-corpuscles of all animals, and 

 " apparently in every tissue in the body. The 

 author enumerates a great variety of organs in 

 which he has observed the same kind of fila- 

 ments." " And if the author's view of iden- 

 tity in structure between the larger and the 

 smaller filaments be correct, it follows that 

 spirals are much more general in plants them- 

 selves than has been hitherto supposed ; spirals 

 would thus appear, in fact, to be as universal 

 as a fibrous structure." " Valentin had pre- 

 viously stated, that in plants all secondary de- 

 posits take place in spiral lines. In the in- 

 ternal structure of animals, spirals have here- 

 tofore seemed to be wanting, or very nearly so. 

 Should the facts recorded in this memoir, how- 

 ever, be established by the researches of other 

 investigators, the author thinks the question in 

 future may perhaps be, where is the ' secon- 

 dary deposit' in animal structure, which is not 

 connected with the spiral form ? The spiral in 

 animals, as he conceives he has shown, is in 

 strictness not a secondary formation, but the 

 most primary of all ; and the question now is, 

 whether it is not precisely so in plants." 



As these speculations profess to be grounded 

 solely on observations of particular structures, 

 of which muscle is one, I shall make no apo- 

 logy for applying my few remarks solely to the 

 account of this structure, which is all that can 

 properly be considered here. A renewed ex- 

 amination of this tissue has confirmed, fully 

 and decisively to my own mind, the account 

 I gave of it in 1840, and which was the result 

 of two years' study. 1. I find that when the 

 natural and ready cleavage happens to be into 

 fibrillae (and I do not pretend to explain why 

 this cleavage should be at one time into fibrillce 

 and at another time into discs, I only know 

 the fact,) these solitary and isolated fibnllse do 

 not present any such central longitudinal 

 groove, as Dr. Barry describes, to indicate 

 their double nature: that the cross lines are usu- 

 ally transverse, and not oblique, by which I 

 mean that the spaces they bound have a rectan- 

 gular outline, so sharp and definite, that the 

 mind rests entirely satisfied that there cannot 

 be two opinions concerning them, between 

 any who have examined the object in one of 

 Powell's best microscopes, and with the use of 

 that admirable definer and clarifier of the 

 image, the achromatic condenser. That right 

 angles can be produced by a spiral, whether 

 double or single, however distorted by accident 

 or violence, it is impossible to conceive. That 

 these transverse lines may sometimes become 

 oblique by irregular traction, such as is almost 



necessarily applied in preparing the object, is 

 most easy to understand, if we bear in mind, 

 that the substance in the different spaces which 

 they circumscribe is onti united mass. 2. The 

 transverse cleavage of the elementary fibre, 

 which I first showed to be occasionally so com- 

 plete as to separate it into discs, cannot be 

 reconciled with Dr. Barry's statement. For 

 the surfaces of such discs present, as in Jig. 

 288, a fine granular aspect, and no ends of 

 doubly spiral threads. And the definite and 

 beautiful appearance presented by a transverse 

 section of the fibre in all animals, but espe- 

 cially in Birds (jig. 290), is totally at variance 

 with his views : for the particles there dis- 

 played are highly refracting, round, and not 

 aggregated in pairs. The condition repre- 

 sented in fig. 289 is not less opposed to them. 

 Other proofs might be adduced, but they 

 would lead to greater detail than is compatible 

 with the form of the present publication; and 

 perhaps they will be allowed to be unneces- 

 sary. 



6. Of the corpuscles of the elementary fibre. 

 The elementary fibres always contain, among 

 their primitive particles, a number of corpuscles, 

 which either are, or are analogous to, the nuclei 

 of the cells of development, of which this 

 and other structures have originally consisted. 

 These corpuscles are visible in the early stages 

 of growth (fig. 291), but disappear towards 

 the close of foetal life, as the lines resulting 

 from the deposit of the contractile particles 



Tig. 291. 



Elementary fibres from the pectoral mitscle of a foetal 

 calf about two months after conception, shewing the 

 corpuscles at a, a, a. Magnified 300 diam. 



Fig. 292. 



Elementary fibre from the lana of the Libellula, in 

 an early staye of development, shewing the central 

 row of corpuscles. Magnified 300 diam. 



Fig. 293. 







Elementary fibre from the leg of the large Meat-fly 



( Alusca vomitoria). 



a, a, line of termination of the fibre, along which 

 the tendon (6) is attached to it. 

 c, central series of corpuscles. 

 Along the margin the sarcolemma is elevated by 

 water, (which has been absorbed,) and is thereby 

 shown to be adherent to the margin of the discs. 



