8 Mr. T. Smith on the Muscular Structure and Functions 



directions. All muscular tissue, from being transparent before 

 immersion in boiling water, became opake and white after it. 

 The transparency of the muscular fibre of clear-blooded ani- 

 mals, such as the cod, whiting, &c. is obvious ; and in red- 

 blooded animals the transparency of the fibre permits the co- 

 lour of the blood to be seen through it. Tendon or ligament, 

 from being white and glistening, became semitransparent and 

 yellowish in boiling water; and purely membranous tissues, 

 whose office is akin to that of ligament, remained transparent 

 after immersion in boiling water, as they were before it. — From 

 these facts I have ventured to deduce the following test, by 

 which the muscularity of transparent animal tissue may, if the 

 principle appears well founded, be tried. 



Test. — Immerse in water boiling hot the transparent part of 

 animal tissue to be tried : If it contract about one third part 

 of its length and become opake and white, it is muscular: if 

 it does not contract, it is not muscular, though it become white: 

 if it contract more than one third, and remain transparent, it 

 is of a ligamentous nature. 



The late Dr. Young, it will be remembered, taught that the 

 crystalline lens consisted of a muscular and tendinous structure 

 arranged in concentric layers and intermixed with a gelatinous 

 substance, and that by the action of the muscular parts of the 

 layers the convexity of the lens was adapted to the different 

 distances of objects. The entire want of communication be- 

 tween the lens and capsule by means of nerves and blood-ves- 

 sels, on which anatomical writers appear to be agreed, is a 

 strong objection to Dr. Young's hypothesis, — not to mention 

 the perfect fluidity of the foetal lens, so very unlike any other 

 muscular or tendinous part at the same period. But to re- 

 move all doubt I plunged the lens, deprived of its capsule, in 

 boiling water. If Dr. Young's opinion were correct, the lens, 

 from the contraction of both the muscular and tendinous parts 

 of each coat, ought to have become much more spherical, and 

 we should have been able, on separating the intervening co- 

 agulum of gelatinous substance, to obtain a succession of thin 

 transparent tendinous layers, surrounded by the muscles at- 

 tached to it, made white by the boiling water. But in number- 

 less instances which I tried, the lens was not found to undergo 

 the smallest appreciable increase of sphericity. It became 

 opake and white, but continued of the same diameter and 

 thickness after immersion in boiling water as it was before. 

 It therefore is not muscular. 



A very different result was obtained when the lens, covered 

 by its capsule, was immersed in the same manner. The lens of 

 a cow, with its capsule around it, measured in diameter 0*7 

 inch, in thickness 0*5 inch, before immersion. After it had 



