Page:The third Huxley lecture.pdf/18

14 these being diffused through a due proportion of liquor sanguinis, the vessels present a pallor which would surprise anyone who had seen only the ordinary demonstrations of the circulation, but which might have been anticipated from the appearance, when in health, of the highly vascular sclerotic with its investing conjunctiva, "the white of the eye."

Such a method of arranging the foot could not be carried out if the animal were able to struggle; but this was effectually prevented in the following way;—The frog, wrapped in cold, wet lint, is held in the left hand, and the head, left exposed for the purpose, is depressed with the forefinger so as to stretch the ligament between the occiput and the first vertebra. The junction between the brain and spinal cord is then divided with a tenotome, after which the creature remains perfectly passive as long as may be desired. Comparatively dull though we know sensibility to be in an animal so low in the scale as the frog, it is a comfort to feel that this method must be attended with exceedingly little pain. That caused by the division of the cord is probably almost as momentary as the stroke of the tenotome; and sensibility as well as motion being abolished in the limbs, the creature cannot feel the tying of the naturally sensitive toes or the subsequent dragging upon them.

This arrangement had the further great advantage of allowing an irritant, even in the form of a drop of liquid, to remain undisturbed at the particular spot to which it was applied, instead of being diffused over