phalon left respiration continues longer but I have never seen it last more than a day and a half.

It seems indeed wonderful to see animals sometimes after a

slight puncture of some part of the encephalon with the point of a needle, turn round, just like a horse in a circus, or roll over and over for hours and sometimes for days, with but short interruptions.

Parts producing turning or rolling after an injury on the right side.

Turning or rolling by the right side.

1. Anterior part of the optic thalamus (Schiff).

2. The hind parts of the crus cerebri (Schiff ).

3. The tubercula (Flourens).

quadrigemina

4. Posterior part of the processus cerebelli ad pontem (Magendie).

5. Place of insertion of the auditory and of the facial nerves (Brown-Séquard and Martin-Magron).

6. Neighbourhood of the insertion of the lower roots of the par vagum (Brown-Séquard).

Turning or rolling by the left side. 1. Posterior part of the optic thalamus (Schiff).

2. Some parts of the crus cerebri near the optic thalamus (Brown-Séquard). 3. Anterior and superior parts of the pons varolii.

4. Anterior part of the processus cerebelli ad pontem (Lafargue).

5. Place of insertion of the glosso pharyngeal nerve (Brown-Séquard).

6. Spinal cord, near oblong medulla (Brown-Séquard).

While rotation takes place it is easy to ascertain, 1st, that it is not its production by contractions resembling those of voluntary movements which causes the rolling or the turning; 2nd, that some muscles are in a state of tonic contraction; 3rd, that the trunk and neck of the animal are bent by a spasmodic action on the side of turning if it has a circus movement, and that it is bent like a corkscrew, as much as the bones allow, in cases of rolling ; 4th, that sensibility and volition may remain, and there are frequent efforts to resist the tendency to turn or roll.

And now, to add to the strangeness of the fact, in this last case the muscles remain contracted sometimes for hours, sometimes for days and weeks.-Idem, Lancet, No. 1,841, pp. 599-601.

(137.)-M. Flourens has found that the section of the semi-circular canals, in certain animals, is followed by a strange disorder of movements, and sometimes by a rotation (circus movement). I have ascertained that the phenomena observed in these experiments do not depend on the section of these canals, as this operation may not cause these phenomena, but that they are the result of an irritation of the auditory nerve, from the drawing upon it by the membranous semi-circular canals at the time we divide them. In frogs and in mammals the direct irritation of the auditory nerve is followed by the most interesting phenomena. It is well known that in frogs

the peripheric extremity of this nerve is enclosed in a bag containing carbonate of lime; as soon as this bag is laid bare and slightly touched, and still more if it be punctured with a needle or a bistonry, the anterior limb, on the opposite side, is thrown into a state of slight convulsion, and kept almost constantly in a spasmodic pronation, and almost at every attempt to move forwards the animal turns round on the side injured. As long as it lives (many days, or even many months) these phenomena may be observed, although not quite so marked as immediately after the injury or after the first twenty-four hours. In mammals the least puncture of the auditory nerve causes rolling, just as after the irritation of the processus cerebelli ad pontem; violent convulsions then occur in the eyes, the face, and many muscles of the neck and chest. The doctrine that the nerves of the higher senses are not endowed with general sensibility (i. . are not able to cause pain) seems not to be true with regard to the acoustic nerve; at least, the signs of pain given after an irritation of this pretended nerve are often as great as those observed after an irritation of the trunk of the trigeminal nerve.-Idem, Lancet, No. 1,842, p. 625.

(138.)-I have now to speak of the condition of animal heat in cases of alteration of the spinal cord and the encephalon. The following conclusions may be drawn from a great many facts bearing on the subject. 1st, that usually anesthesia is accompanied by a diminution of temperature; 2nd, that hyperesthesia almost always co-exists with increased temperature; 3rd, that in paralysis, without either a notable hyperesthesia or anesthesia, the temperature is nearly normal. I must remark that the state of heat of a part is due to the amount of blood, the degree of heat of this fluid, the exposure of the part to the influence of the temperature of the surrounding medium, and the temperature of this medium.-Idem, Lancet, No. 1,843, p. 652.

(139)-Professor Brown-Séquard is continuing with indefatigable labor the series of his valuable researches and experiments upon the physiological pathology of the nervous system. His communications to the Academy of Medicine have formed the most marked features of the recent sitting of this learned Society. As you will doubtless give full attention to these researches when they shall have been published in extenso, I shall only mention a few points thereof so as to keep au courant of everything that crops up here at the very moment of the event. My letters must be photographs of the passing occurrences of the day. M. Brown Séquard's most recent researches bear upon the consequences produced by certain lesions of the corpora restiformio and the sciatic nerve in guinea-pigs. According to the illustrious experimenter, when the sciatic nerve is severed in

guinea-pigs on exciting a certain determinate part of the face which he names le zone épileptogène epileptiform phenomena are produced. Excitement of no other portion of the face can induce an attack of epilepsy. But in order that the phenomena may take place, it is necessary that the excitement should be produced on the side corresponding to the limb where the nerve has been divided. M. BrownSéquard showed two guinea-pigs to the Academy and reproduced his experiments before the assembly. M. Colin, one of the members, mentioned that he had often performed the division of the sciatic nerve without being able to induce epileptiform attacks. M. BrownSéquard's experiments on the restiform bodies are equally interesting and curious. One of the results of injury to the corpora is the production of hæmorrhage under the skin of the ear. Hitherto certain kinds of hæmorrhage had been observed as the result of injury to the nervous system, for instance hæmorrhage of the kidneys in diseases of the spinal cord and hæmorrhage of the intestinal tube in diseases of the brain. But the fact now illustrated is remarkable on account of its constant occurrence. Another result is the production of dry gangrene of the ear, which, according to the experimenter, is not the consequence of paralysis produced by the section of the restiform bodies. M. Brown-Séquard exhibited a guinea-pig showing this kind of gangrene. At the last meeting of the Academy he again adverted to the subject, and stated that the precise point of the restiform body which he excited in order to produce hæmorrhage and sphacelus was the nib of the calamus scriptorius. Some particulars he added tended to show that this situation was really the one which he excited in his experiments, for instance, the paralysis of the tongue and anæsthesia of the lips-the animal could not hold the food which was introduced into its mouth. It was a well known fact that the hypogassal nerve and fifth pair take their origin in the neighbourhood of the calamus scriptorius. M. Brown-Séquard concluded by pointing out the strict analogy which exists in a great number of cases between the phenomena determined experimentally in animals and those which are observed clinically in man. On account of the extreme interest of these experiments M. Bouillaud has requested M. Brown-Séquard to repeat his experiments before a certain number of the members, which has been assented to.-Lancet, No. 2,380. p. 514.

(140.) In the course of some recent experiments on the establishment of artificial epilepsy in guinea-pigs Dr. C. Westphal has been over the same ground as that explored by M. Brown Séquard, and fully corroborates the results at which the latter observer arrived. He adds, however, some new and interesting facts. Thus, he found that if one or two slight blows on the side of the head are given to a guinea-pig they are sufficient to bring on an epileptiform attack, after which the animal again recovers its liveliness, or it remains heavy for some time and then exhibits a kind of rotatory movement

like those shown by Schiff to occur in rabbits after lesion of the crus cerebri.

If the animal survives the blows, a similar epileptigenic zone is created as in the guinea-pig treated on M. Brown Séquard's method by lesion of the medulla oblongata at certain points or section of the sciatic; and as in these last cases, the zone is near the angle of the lower jaw. Before the zone is well established, and four weeks are usually required for this purpose, the animals betray the presence of some irritation at this part by frequently scratching it. After it is established slight punching will induce tonic and clonic spasms, though the sensibility of the skin is here diminished. The rapidity with which the zone can be established may be increased by striking the animal's head on successive days, and the excitability of the zone endures for a period varying from six weeks to six months. The condition is hereditary. M. Westphal set himself to ascertain the nature of the changes induced by the blow or blows. That the condition is not produced by any alteration in the integuments is shown by the circumstance that the fits occur when the exposed skull is struck.-Lancet, No. 2,528, p. 195.

(141.) Dr. Brown Séquard has with great kindness related to me his more recent researches, and shown me the interesting little animal upon which he is now experimenting. I have therefore the pleasure of being able to speak of them de visu, and of adding some interesting details of the note which I sent you two weeks ago. If you remember I then mentioned that the professor's recent researches were upon some of the effects of section of the sciatic nerve and injury to the corpora restiformia in guinea-pigs. A great number of the animals were shown to me in which the sciatic nerve had been severed, and in all the zone épileptogène did exist. I mean one single spot by exciting which the fit was immediately produced. Pinch wherever you like independently of that situation, and though the animal will not like it, and will scream more or less, there is nothing abnormal; but as soon as you excite the particular spot it goes into a fit. In this situation, which may be easily circumscribed, extending from the ear to the eye round below the jaw, and backwards to the shoulder-blade, there seems to be an obvious impairment of nutrition, the hair is much less abundant, parasitical animals are found there, &c, and besides sensibility is considerably diminished. The fits produced are quite similar to those brought on by section of the lateral half of the spinal cord.

Dr. Brown Séquard showed me some animals in which the paw of the limb where the sciatic nerve had been divided was more or less injured. This, he observed, was not a spontaneous injury, which must be attributed, as had been thought, to the division of the nerve. The dragging of the paralysed limb produced a slight abrasion, and

as soon as there was a drop of blood, the little animal set to gnawing the insensible extremity. It is also the case with rabbits. There must be, however, a drop of blood to excite the voracity of the animals. In some of them two of the claws of the feet, the two outer ones, animated by the great sciatic nerve, which alone is severed, had fallen off, while the remaining claw and middle one, animated by the little sciatic nerve, was unimpaired. By wrapping up the limb in a bag as soon as section of the sciatic nerve is performed the experimenter prevents an injury occurring.

With regard to his other series of experiments, those in the corpora restiformia, the professor showed me a great number of guineapigs in which I could trace the effects of injury to that particular part of the nervous system. The ears of several guinea-pigs showed the appearance of dry gangrene In some of the animals half of the ears had already fallen. The aspect produced by the solution of continuity along the edge of the ear is quite distinct from that of a bite. In a bite the little portion of the ear seems cleanly cut off, whereas in dry gangrene it appears to have crumbled off. I have noticed the remains of two or three hæmorrhagic clots which had formed on the ear.

To conclude, I may just mention that Dr. Brown-Séquard was much surprised when some of the French journals stated that he had neglected to note the occasional occurrence of hæmorrhage in the ears of insane people. The fact is that the very object of the illustrious experimenter in mentioning the phenomena which he observed in guinea-pigs was to show that the hæmorrhagic clot observed on the ears of mad patients, and concerning the etiology of which there is still much discussion, may be due to purely internal nervous causes, and not to external violence, his chief aim in every one of these experiments being their application to the pathology and therapeutics of the human species.--Lancet, No. 2,382, p. 586.

(142) Nothnagel employs a new method for the determination of the functions of the brain. His observations are made mostly on rabbits. An incision is made in the scalp; the skull is perforated with a needle. Through the canal thus formed in the bone a very small drop of a concentrated solution of chromic acid is injected by means of a hypodermic syringe with a very slender nozzle. The scalp wound is then united by suture, and the animal does not seem to be affected, except with regard to the functional derangement incidental to the lesion. Generally they survive the operation two or three weeks, and die from causes which Nothnagel cannot explain, no constitutional symptoms being developed.-The Doctor, November 1st, 1873, pp. 214 and 215.

(143.)-Professor Nothnagel, of Freiburg, contributes a paper to the last of Virchow's Archiv., Band lvii. (Heft. 2, p. 184), containing