ments of the brain, and the blood pressure within the cranium by means of a manometer screwed into an artificial opening made in the skulls of dogs.-Dr. Rutherford, Journal of Anatomy and Physiology, 1867, pp. 35-89.

(74.) He gives the results of a number of experiments upon the crura cerebelli of rabbits. The author working under the direction of Professor Eckhard, has taken great care to ascertain the exact position and extent of the lesion which he inflicted.

He gives an exact description of his mode of operating which will prove of not a little service to those who may wish to perform experiments, whether for the purpose of research or demonstration.

In his experiments on the "tract of the crus erebelli, formed by the anterior and posterior crus" he found that very much the same effects followed a variety of injuries to the tract comprehending punctures to the depth of one, usually two millimetres, some in its middle, some on its outer, others on its inner side. Irregular but not violent contractions followed these injuries. Voluntary movement was slightly disturbed. Some animals showed a tendency to lie upon the injured side.

In a second series of researches he studied the effect of complete division of this tract. The section was followed by irregular convulsive contractions of varying intensity, extending throughout the entire body.

Voluntary movement seemed to be entirely abolished. The animal lay upon the injured side and fell always into this position when it was placed in any other. Some animals were observed in this state for three or four hours, others died from the hæmorrhage, which the operation for exposure of the brain had occasioned.Fournal of Anatomy and Physiology, 1869, p. 208.

(75.)-At the recent meeting of the British Medical Association, Dr. Brunton read a paper communicated by Dr. Ferrier, containing an "Abstract of Experiments on the Brains of Monkeys, with special reference to the Localisation of Sensory Centres in the Convolutions." The experiments, which were conducted by trephining and the destruction of the sensory centres by means of a red hot wire, led to the following results: These centres are bilateral, so that when one of the centres of touch was destroyed there was loss of tactile sensibility in the corresponding half of the body. Stimulation of the centre of hearing caused the animal to prick up its ears, as if it heard something, while destruction of the whole of this centre rendered the creature totally deaf. Destruction of the centre of vision corresponding to one eye (e. g., the right) only rendered the

animal temporarily blind in that eye, the function, after twenty-four hours, being carried on by the opposite centre. In the discussion that followed Dr. Nairne pointed out that other observers had arrived at conclusions different from those of Dr. Ferrier, and that the brain of a monkey could not be taken as exactly similar to that of a man ; but Dr. Brunton thought the mistake made by German and other investigators who differed from Dr. Ferrier was, that they took the brains of animals lower even than the monkey to correspond with that of man. M. Dupuy had arrived at different results. He said that he had found that when the centres of motion on one side of the brain were removed paralysis followed for a short time throughout the corresponding part of the body, but that when the centres were removed from both sides of the brain there was no paralysis at all.— Lancet, No. 2712, p. 289.

(76.) Dr. Brown-Séquard, in a lecture before the Boston Society. of Natural History, published in the Boston Medical and Surgical Journal dissents altogether from the conclusions that have been drawn on this subject, and which have lately occupied so much attention.

Our readers will remember that Fritsch and Hitzig, followed by Charcot, Ferrier, and others, concluded that the fronto-parietal convolutions of the brain are the centres for the voluntary movements of definite groups of muscles; but Brown-Séquard explains the facts in quite another way.-The Doctor, October 1st, 1875, p. 181.

Professor Hitzig refers to Burdon-Sanderson's experiments and remarks" that the localised points on the surface of the brain given by Burdon-Sanderson do not correspond with those described by himself."Journal of Anatomy and Physiology, November 1874, p. 210. [See also p. 397.]

(77.)-On the Suffocation of Animals.

About the year 1860 the Royal Humane Society received several suggestions from Dr. Silvester for restoring suspended animation in persons apparently drowned. Other methods were shortly afterwards placed before the society, on the merits of which that body felt itself unable to decide, and consequently its committee desired the Royal Medical and Chirurgical Society to investigate the several proposals, without indicating the tests which that learned body should apply, or the means they should adopt. It is important to bear in mind that the Royal Humane Society is in no way answerable for the course taken by the Royal Medical and Chirurgical Society, and that they were not even aware, until the delivery of the report from which the following extracts are made, that experiments on animals had been performed by the Committee of Investigation.

Seventy-six experiments were made on animals, in only a few of

E

which anesthesia was present; and after the terrible sufferings caused by plugging their windpipes to suffocate them, holding them under water, and in some cases restoring them to life for further experimentation, burying their heads in liquid plaster of Paris or mercury, cauterising their bodies with an iron heated to a white heat, &c., &c. the committee, it will be seen, report that they were unable to recommend any material improvement in the plan adopted by the society.

Report of the Committee appointed by the Royal Medical and Chirurgical Society to investigate the subject of Suspended Animation.

Members of the Committee.-C. J. B. Williams, M.D., F.R.S.; C. E. Brown-Séquard, M.D., F.R.S.; George Harley, M.D.; W. S. Kirkes, M.D.; H. Hyde Salter, M.D., F.R.S.; J. B. Sanderson, M.D.; W. S. Savory, F.R.S.; E. H. Sieveking, M.D. (ex officio). At the first meeting of the committee it was resolved to pursue the inquiry—

By means of experiments upon living animals.

By means of experiments upon the human body.

Two sub-committees were forthwith appointed for these purposes.

Report of the Sub-committee appointed to investigate the subject of Suspended Animation by means of experiments upon living animals.

In investigating anew the subject of apnoea by means of experiments on the lower animals, it seemed expedient to observe, in the first place, the principal phenomena of apnoea in its least complicated form, viz., when produced by simply depriving the animal of air.

The following plan of effecting this was adopted :-The animal was secured on its back, and the trachea was exposed by a single incision in the mesial line of the neck. A ligature having been passed round it, it was opened by a vertical cut, and a glass tube, as large as could be conveniently inserted, was passed into it for a short distance downwards, and firmly secured by the ligature. Through this tube, while patent, the animal breathed freely, but the supply of air could be at once completely cut off by inserting a tightly-fitting cork into the upper end of the tube. It was ascertained by separate experiments that the tube thus plugged with the cork was perfectly air-tight.

The duration of the heart's action was conveniently ascertained by means of a long pin inserted through the thoracic walls into some part of the ventricles. So long as the heart continued to beat the pin moved, and its motions were thus recorded for some time after the cardiac sounds had ceased to be audible :

Experiment 1.-A full-grown healthy dog was suddenly deprived

of air by plugging the tube placed in the trachea in the manner already described. Its first struggle occurred in twenty-five seconds; its first respiratory effort was not recorded, its last took place at four minutes forty seconds, and its last heart's beat at six minutes forty seconds, or exactly two minutes after the last respiratory effort.

[Eight similar experiments were performed on dogs, rabbits, and one cat. In three of these the plug was withdrawn at about fourand-a-half minutes, but the animals were found to be dead.]

From nine experiments it is seen, that in the dog the average duration of the respiratory movements after the animal had been deprived of air, is four minutes five seconds, the extremes being three minutes thirty seconds and four minutes forty seconds. The average duration of the heart's action on the other hand is seven minutes eleven seconds, the extremes being six minutes forty seconds and seven minutes forty-five seconds. Lastly, these experiments lead to the belief that on an average the heart's action continues for three minutes fifteen seconds after the animal has ceased to make respiratory efforts. The extremes being two and four minutes respectively.

In the case of the three rabbits experimented upon, we find that on an average they ceased to make respiratory efforts in three minutes twenty-five seconds; that their heart's action stopped in seven minutes ten seconds; and, consequently, that the interval between the last respiratory effort and the cessation of the heart's action was three minutes forty-five seconds.

[Then follows a series of experiments in which the plug was withdrawn at different intervals, and the dogs delivered from the pains of death, and were subsequently operated on again. The Committee say:-]

These results lead to the conclusion 1st, that a dog may be deprived of air during a period of three minutes fifty seconds, and afterwards recover without the application of artificial means; and 2ndly, that a dog is not likely to recover if left to itself after having been deprived of air during a period of four minutes ten seconds.

For some time after the occlusion of the tube in the trachea the force of the respiratory efforts was so remarkable that it was determined to adopt some means of measuring it.

The following were the results :

Experiment 15.—A medium-sized dog was treated in the above way. The respiratory efforts commenced at two minutes five seconds. As apnoea advanced they became more powerful, and from three minutes twenty seconds and onwards they were very violent till four minutes forty-five seconds, when they ceased. The needle showed the heart to be moving up to eight minutes. This dog drew the mercury up the tube, by its violent inspiratory efforts, a height of four inches, and that height was attained in almost the last attempts at respiration, four minutes forty-five seconds after the establishment of the apnoea. On examination the lungs were found

to be congested, but there were no ecchymosed spots or blood in the tubes.

[Then follow similar experiments which produced similar congestion of the lungs.]

In the following experiments the great force of the inspiratory efforts was demonstrated in another way.

Experiment 18.-A guinea-pig was held so that its nose was immersed in mercury, the animal being upside down, and the nose inserted sufficiently deep in the mercury to prevent the possibility of getting any air. The respiratory efforts commenced at thirty-five seconds, and ceased at one minute thirty-seven seconds. On examining the lungs they were found full of globules of mercury, which had thus been drawn up by this weak animal a distance of an inch or two, and that in spite of gravitation.

Experiment 19.-A terrier was deprived of air by plunging its head into liquid plaster of Paris, the object being, to see, through the whiteness of the plaster, whether any of the fluid obtained access to the lungs. Respiratory efforts commenced at one minute thirty-five seconds, and ceased at four minutes, the heart beating till five minutes. On examining the lungs the white plaster was found throughout the bronchial tubes.

From these preliminary experiments on the effects produced by simply depriving an animal of air, the Committee passed on to the consideration of drowning. The first point to be ascertained was, "for what period can an animal be submerged and yet recover without the aid of artificial means?"

Experiment 20.-A medium-sized dog was fastened to a board and submerged in a large bath. It was removed in four minutes, but although the heart went on acting for four minutes and a half longer, it neither gasped nor moved.

[Two similar experiments follow.]

It having been thus ascertained that four minutes' drowning kills, it was determined gradually to shorten the time, in order to find out what was the limit of time at which immersion proved fatal.

Experiment 23.-A dog was bound as before to the board and immersed for three minutes fifteen seconds. On being taken out of the water no respiratory efforts were made; the dog was dead. Bloody froth escaped from its mouth, and its lungs were full of the same material.

Experiment 24. The same as above, but the dog's head was kept under water two minutes only. The dog gasped once or twice and then died. Lungs full of blood and watery froth,