Ernest Nicolas Joseph Onimus

“ Among animals deprived of the cerebral lobes there is another curious and constant phenomenon, the forced and continual tendency to maintain an equilibrium. We have seen in the frog, the carp, the eel, the pigeon, the goose, mammals, etc., that every time we disturbed their centre of gravity, immediately there took place a series of coordinated movements which have the single aim of restoring the equilibrium. A decapitated insect remains always firmly posed on his feet and can take no other position. ”

“ If we put a drop of vinegar on the foot of a frog in which the cord is separated from the brain, the foot retires at first, then the other foot makes coordinated movements to get rid of the cause of irritation. The frog which has lost only its cerebral lobes commences, on the contrary, to make many leaps; afterward it moves only one or other of its feet. In the frog where the cord is severed, to each excitation succeed muscular contractions; these are always in proportion to the energy of the excitation. ”

“ To act, they must receive an impulse either from without or within. Exterior excitement we can produce artificially, by acting on the peripheral nerves; interior excitation is produced by the cerebrum, and we may say that, from the point of view of physiology, the cerebrum has no other function than to put in action the different motor centres. It is a simple excitant, with this important difference—that external impressions can determine only a certain number of movements, while the brain provokes an immense variety. ”

“ In case the cerebral influence is abolished, the locomotive centres become absolutely independent, as is shown by the forced automatic movements. Again these centres may be excited by a tumor, or a prick, and then their dependence upon the cerebral lobes ceases at once, notwithstanding the anatomical communications which still exist. It is in these cases that the compulsion, from the instant of the lesion, becomes invincible, and forces the animal into movement. The locomotive centres become active, and, as long as the excitement lasts, the animal is completely under their influence. ”

“ When the cerebral lobes are removed, animals cannot remain lying on the back. They always seek to recover their normal attitude, and, consequently, when they have deviated from it, all their efforts go to recover equilibrium. It is at this moment that the four limbs concur to execute the gyratory movement. There are two factors in the motion of rotation: the first is the contraction of the muscles of the injured side which makes the animal lean over and bear down on that side ”

“ To employ the usual expression, one is nature; the other, second nature. If you remove the cerebral lobes of a duck that has never been in the water, and then place it in water, it will swim regularly; but it will not, like an old duck deprived of its cerebrum, make certain habitual movements of the neck. The old pigeon, although without its cerebrum, when asleep places the head under the wing; and he often even dresses his feathers. Young pigeons have never been observed to perform these acts, while they execute other movements normally like old pigeons ”

“ In the frog with the cord joined to the cerebellum alone, the excitation can take place without producing movement; but, be it feeble or strong, from the moment reflex action begins the result is the same—a movement of the body which produces a leap. ”

“ The loss of equilibrium acts more energetically than the stimulus of the water on the skin.
Tip a carp to the right or left, at once it recovers its normal attitude. If you place a duck on one of its sides, either on the ground or in the water, it at once corrects itself and comes upright. The cerebellum alone controls equilibrium, as is easily proved by experiment. When it is wounded or destroyed, the animals He indifferently on one side or the other, and make no movements to recover the lost equilibrium. ”

“ Reciprocally, if the frog is motionless on the surface of the water, and if we set the fore-foot in motion the hind-foot immediately begins to move, and the animal swims. In a word, to speak generally, when an animal is deprived of its cerebral lobes, if one limb begins to move the others immediately follow; if one comes to rest, the others tend to cease moving. ”

“ At the same time, the entire animal leaned a little to the right side. This inclination of the body is neither constant nor inevitable with animals which have only the movements in a circle; it is, on the contrary, constant and forced with those that have the turning motion.
The attitude of this frog changed, and was even reversed, when it was chloroformed; the left side, which was more drawn up, where the muscles experienced a tonic contraction predominating over those of the right side, became then more feeble. ”

“ If we increase this contraction, we draw over a little more in the same direction, until we come to lie completely on one side, and at this moment there supervenes a movement of rotation, almost instinctive, which makes us spasmodically take the normal position. ”

“ Another peculiarity of movements that take place when the cerebral lobes are removed is, their continuation when once commenced. On the earth a frog without a cerebrum, when irritated, makes two, three, or more leaps; he rarely stops with one. Placed in the water he continues to swim till he encounters an obstacle. The pigeon continues to fly, the duck and the goose to swim. ”

“ If a frog is motionless on a piece of board, and you slowly lower the board in the water so that he is immersed, in most cases, notwithstanding the stimulus of the water on the integuments, the frog will remain immovable. ”

“ The locomotive apparatus acts without restraint, and we may, therefore, say that the movements are more normal than in the normal state. In the second place, when the cerebrum is removed the movements only commence after excitations; they cannot start themselves. The frog must be put in the water to swim, and the pigeon thrown in the air to fly. In animals without a cerebrum the physiologist can determine such or such an act, limit it, arrest it ”

“ The striking thing about it is, the continuation of the state determined at first by an impulse from without; and we cannot help associating these facts, about animals deprived of their cerebral lobes, with the characteristic properties of inorganic matter. Put agoing, the animal without a cerebrum continues to move till the exhaustion of the conditions of movement, or till it encounters resistance. Put in repose, it remains inert till some exterior cause sets it in motion. It is inert living matter. ”

“ Duck, wounded in the Right Side of the Cerebellum
we may say that, in an animal from which have been taken only the cerebral lobes, we might obtain a movement of rotation if, as soon as the animal is on his fore-feet, we turn him on his back; external interference would replace in this case the action produced by lesion of the pons Varolii. ”

“ A Frog in which the Cerebrum has been removed.
We may conclude that the movements of animals, whether superior or inferior, are produced by certain special mechanisms, or by locomotive centres, situated at the base of the brain. These centres are essentially passive; they have no spontaneous action, and come into activity only when excited by peripheral stimulus or by the brain. ”

“ The limbs of the affected side are not really paralyzed, but, nevertheless, their movements are more limited, they are not so extended nor so various, and their action no longer coincides with that of the healthy side. ”