370 Dr. Barry on a Main Cause of Discordant Views 



In a few seconds they had hardened and recovered their elasti- 

 city. After having been minutely examined for the detection 

 and breaking up (with a needle) of adhesions that might have 

 occurred in the softening, the wires were gently extended, and 

 found to spring back into the previous comparatively contracted 

 state ; thus beautifully illustrating the movements of the muscu- 

 lar fibril. The union seen in this model of the two spirals at 

 the end of the fibril, is to be inferred from analogy with what I 

 have elsewhere shown in cilia. 



I cannot refrain from once more recommending the heart of 

 some reptile as especially adapted for the examination of the 

 fully-formed muscular fibril. The heart of the Turtle has often 

 afforded me unquestionable specimens of the twin spiral*; but 

 far more easily obtainable is that of the common Frog. 



In order thoroughly to understand the structure of this tissue, 

 however, it is essential to see it in its most incipient state, and 

 patiently to follow it through every stage. At that early period 

 its elements are very large, of course an immense advantage to 

 the observer. I had this advantage ; and using, as I for the 

 most part did, the larva of the large Jersey Toad (which a friend 

 informs me is a variety of the common Toad), I had a further 

 advantage, the first elements of muscle in that larva being of 

 enormous size. Out of these I saw spirals to arise of corre- 

 sponding size ; so large as to enable me not only to discern the 

 particles of which they were composed f, but also to observe that 

 by division and subdivision spirals pass into membrane, forming 

 for instance the sarcolemma, the cells of cartilage and the cells 

 of coagulating blood. [An observation confirmed ten years after 

 by Agardh, who in his paper De cellula vegetabili fibrillis tenuis- 

 simis contexta, Lundae, 1852, shows not only that vegetable 

 membrane is formed by fibre, but that the fibre forming vegetable 

 membrane has the very structure that I maintain to be that of 

 all organic fibre, being composed of spirals which in number he 

 delineates as two, and moreover represents as dividing — each 

 of them into a fasciculus of spirals J.] And of course I refer 

 to spirals the gentle undulations which constitute the first move- 

 ments of the Tadpole's tail ; in other words, I conclude that it 

 is the spirals that arc endowed with contractile power ; for to 

 what else is to be attributed this power where all that can be 

 recognized as muscle is made up of spirals ? 



The eye, when thus accustomed to spirals of large size, dis- 

 cerns them though exceedingly minute, as in older muscle. 



* See, for instance, in the Phil. Trans, for 1842, plate 7, fig. 56. 

 t Phil. Trans. 1842, plate 8, fig. 68. 

 X Agardh, he, cit. Tab. I. fig. 8. 



