EXPERIMENTS ON IRRITABILITY. 183 CHAPTER XI. ABERNETHY'S EXPERIMENTS ON THE MUSCLES IN "THERE are more things in heaven and earth" than are dreamt of in your philosophy, "Horatio," is a sentiment which, in some form or other, occurs to the most uninformed peasant, and to the most profound philosopher. The very small difference between the acquisitions of the two, however marvellous when viewed abstractedly, sinks into nothing when compared to the secrets of nature which yet remain unexplored. This comparison is the true source of that humility which, while it adds dignity to the acquirements of intellect, is the 184 EXPERIMENTS ON IRRITABILITY. foundation on which we may most securely rest the hope of increasing possessions. The intellectual vision of the wisest man confines him to a very small area, when compared with the boundless realms of nature. There are, indeed, a number of objects within. the range of his perceptions whose nature and relations he has the power of examining; but there are also a multitude of others which, from their dimly-sketched outline, he feels to be beyond the bounds assigned to his limited faculties. One of the most curious things in animals is the rigidity or stiffness of their muscles after death. It is the last effort, as it were, of the living principle. This phenomenon may be indefinitely modified by particular states, by lightning, by poison, and other peculiar conditions, induced by the manner and the period at which the death may have occurred; and in all cases it continues but for a short time. It is the last exercise of that power which resides in muscles or flesh, of contracting, and thus moving the various parts to which it is attached. In a very large sense this power is under the dominion of the will, and enables animals to move as their instincts or their wants suggest. Now it is a curious thing to think that this power can be excited after death by placing the part between two pieces of metal, or galvanising them as it is called, after the name of the discoverer, Galvani. It is difficult at this day to imagine the astonishment of the wife of Galvani, or his pupil, when first they observed the leg of a dead frog thrown into convulsions on being touched by a piece of metal; such, however, was the apparently simple origin of a long series of wonderful discoveries. It has been well observed, however, that "discoveries, ap"parently the result of accident, always imply "the exercise of profound thought;" and this was no less the case in respect to galvanism. A fact, which but for the mention of it to Galvani by his wife might have passed unobserved, was by the scarcely less than creative power of mind, improved into a most important branch of human science. Ignorant as men still remain of the intrinsic nature of the principle or power which gives rise to the phenomenon, the observation. and study of its laws and operations have led to discoveries which in their value, their importance, and their surprising character, yield to no other yet achieved. Abernethy, who at this laborious period of his life had his observation directed everywhere, made some experiments on this power -galvanism-in its relations to the muscles of frogs. His object seems to have been as follows: Fontana (a celebrated physiologist, born in the Tyrol about 1734) had showed that a muscle which could no longer be excited to contract under water, might be excited anew if taken out of the water and exposed for some time to air. This observation had suggested the idea that air was in some way or other conducive to this irritability," as it was termed. Dr. Girtanner OBJECT OF ABERNETHY'S EXPERIMENTS. 187 had also endeavoured to prove that the irritability depended on the oxygen taken into the blood. during respiration, and that the irritability was in a direct ratio to the quantity of oxygen respired, "an opinion which some writers in this country seem disposed to adopt." Abernethy doubted the soundness of such a view, and he accordingly instituted some experiments, in the hope that if he could not absolutely determine the question he might throw some light on it. His experiments were very numerous, but he published only a few of them. We will give one or two. "Having killed a "frog (for he properly objected to experiments on living animals), he experimented on the "muscles of two legs; one was put into a bottle 66 containing oxygen gas procured from manganese, and which was very pure; the other "into a bottle containing atmospheric air; the quantity in each bottle was about six ounces. 66 by measure; the limbs were supported in the "airs, and wholly surrounded by them. After "five hours the muscles had nearly ceased to |