Dr. Barry on the Structure of the Muscular Fibril. 365 



because ce appears to have been separated from ca only as far as 

 d, and because in several adjustments I have observed the ap- 

 pearance of each particle being made up of two slightly dislo- 

 cated (a disposition which is slightly indicated in the last par- 

 ticle at b). I still admit that the portion of fibril, including 

 these four particles from b to d, presents very much the appear- 

 ance of a spiral or twist ; but, since it is the only portion among 

 a very great many fibrils in which I have seen the spiral form 

 (that is, a spiral appearance not obviously caused by dislocation, 

 as in ik, which, as you know, might mislead), I must in the 

 meantime suspend my judgement as to the cause of this seeming 

 spiral." He further remarks : — " As I stated to you in con- 

 versation, I cannot make up my mind as to the nature of this 

 structure;" and adds : — " I shall therefore look with much in- 

 terest for the more full explanation of your observations." With 

 regard to specimens that I had shown him, sent me by Dr. Tho- 

 mas Spencer Cobbold*, from the tentacula of the Actinia, — in 

 which he (Dr. C.) had discovered proofs of the accuracy of my 

 views, — Prof. Allen Thomson, after remarking that they present 

 a clear view of the double spiral, adds : — " I admit that if these 

 double spiral prehensile filaments of the Actinia are contractile, 

 they may be fairly used by you as an argument in favour of your 

 views." Besides this, the Professor admits "the existence of 

 the spirals very clearly — in the heart." 



If all observers were as circumspect in making up their minds 

 as Allen Thomson, science would progress with less of fluctua- 

 tion. The more full explanation of my observations, for which 

 that distinguished physiologist is good enough to say he shall 

 look with much interest, requires however but very few words. 



Divisions such as those we together saw, and which have been 

 most faithfully delineated by him in fig. 2, I had figured in the 

 Edinburgh New Philosophical Journal for October 1843, plate 5. 

 fig. 2; and in Muller's Archiv for 1850 f. When subsequently 

 examining, along with the Professor, a preparation sent me by 

 Dr. Dobie, we found several of the states in fig. 4, which fully 

 confirm and extend the observations now referred to as recorded 

 by myself in 1843 and 1850 J. For this drawing also (fig. 4) I 



* Under-Conservator of the Museum of Anatomy and Physiology in the 

 Universitv of Edinburgh . 



f Taf. XVII. fig. 29. See also Phil. Mag. for August 1852, Plate I. 

 fig. 6. 



X Changes such as those in fig. 4 are obviously intimated by the u cru- 

 cial mark" at h in fig. 2. Concerning this crucial mark, the Professor, in 

 a letter I have since received from him, remarks : — " This was well given, 

 if I remember right, in Dr. Dobie's paper." [Published, I hear, in the 

 Annals of Natural History for February 1849 ; but I have not seen it. — 

 M. B.] 



