of the first member of the chain was stimulated all the muscles contracted.
If this be the case, may we not suppose, as was suggested by Professor Kühne of Heidelberg some time ago, that those parts of certain muscles which are destitute of nerves may be
Fig. 71.—Diagram showing arrangement of apparatus used in demonstrating the action of light on the retina of a frog's eye. A, the eye, having one electrode, b, touching the centre of the cornea, and the other, c, touching the transverse section of the optic nerve; G, galvanometer; D, key. The arrows show the direction of the current.
thrown into action by the stimulus of the negative change happening in adjacent portions of the muscle supplied with nerves? I think this is highly probable.
I shall now endeavour to show you the electrical change produced by the action of light on the frog's eye, a subject on which
