of trees of the same species, the same size, and presumably the same age, standing within twenty feet of each other, on the same kind of soil, cut down the same year, and, so far as he could judge, subject to the same conditions throughout, "one showing a large ring where its neighbor would show only an average one, and in some few cases they showed the opposite." While he can not account for the spasmodic production of single rings of large or small growth, interspersed here and there among those of average size, he has been able to trace successions of large or small rings to some plausible cause. In making some surveys, he had had occasion to refer to two trees which had been marked in the Government surveys of fifty years before, as "witness-trees," to aid in identifying corners. Both were described in the field-notes of those surveys as ash-trees three inches in diameter. One had grown to be eighteen inches in diameter; while the other had added only a half inch to that dimension, but the required rings of growth could be plainly seen under the glass. The former tree had had a good soil on level ground, while all of its adult rivals had been blown down by a tornado which had passed over the spot. The latter tree "stood in dissolved sandstone for soil, on the top of a narrow ridge, between three large oaks, which robbed it of sunlight and rain, and nearly all the soil nourishment. It had but five or six small branches for a top, and but few leaves to a branch; under such conditions it did well even to exist." Mr. Campbell read the history of two oaks as it was revealed to him by the rings and the configuration of the ground. One sprouted from the seed in 1502; the other, twenty feet distant from it, in 1694, or ninety-two years afterward. "In 1731 a tornado from the northwest blew down a still older oak, which in its fall struck against and greatly damaged the top of the one born in 1502." The two younger trees had been freshly cut down when the author examined them. 'Their stumps were about four feet across, and there was not over an inch difference between their diameters, though ninety-two years difference in their ages. The younger had a large, healthy top, no broken or dead limbs, and it had put on rings of growth from the beginning of more than average size. The older one had been injured in its branches by the fall of the still older tree before mentioned (in 1731), and for fifty-seven years had put on very small rings of growth, . . . when a new set of branches developed to take the place of the damaged ones, and the rings began to increase in size and gradually attained to the average. I examined their tops, which coincided with what has gone before. There were the peculiar knots in the top of the older one where dead limbs had rotted off and were healed over. During this delay the younger oak caught up with the older one in size. The size of a tree is a very uncertain indication of its age." Mr. Campbell examined one tree that was six hundred years old, and learned from it that "at the age of about two hundred years it had some ill fortune which caused it to form about one hundred small rings. It then regained its health and formed normal rings for about one hundred and forty years, when another mishap caused small rings till within the last fifty years, when it was putting on fair growths again."
Uses and Nature of Physiological Experiment.—Dr. H. Newell-Martin has replied to an accusation made against him in the London "Zoöphilist," of practicing cruelty in his physiological experiments on living animals. First, he responds to the charge that the experiments are useless, saying: "Every one is aware that in very many cases severe fevers result in death. It is well known to most medical men that most such deaths are due to failure of the heart. This failure is caused by too rapid beat, the organ not getting rest enough between its strokes for nourishment and repair. This quicker beat might be due to any of four or five possible causes. . . . To ascertain which of them was mainly responsible for it, and thus throw light upon the proper means to be adopted to save life, was the object of my research; an object which, I am proud to say, I in large measure attained." In regard to the amount of pain inflicted in the experiments, his first endeavor was "to put out of action, to kill, all parts of the body but the heart and lungs. These do not possess consciousness, and are incapable of suf-
