Imagens das páginas
PDF
ePub

agate their species, but their puppies are epileptic. Seventh; The recovery of automatic movement in some degree is not to be ascribed to the action of the corpus striatum since this is atrophied. It is rather to be considered as a function of other portions of the cortex, which thus take up and carry out the action of the deficient part, but in an imperfect manner. The portion to which the author assigned this vicarious work is the uninjured opposite hemisphere.

In a paper in the American Journal for January, 1887, Dr. E. R. Hun presents an elaborate study of a series of cases bearing upon cerebral localization. The conclusions which he considers justified by his investigations are chiefly as follows: First; The greater part of the cerebral cortex can be divided into small areas, each of which is functionally associated with a definite mode of mental action, and is consequently called the cortical centre for that action. Second; The cortical centres connected with the sensory nerves are situated in the posterior half of the cortex, including the temporal lobe; and the cortical centres connected with the motor nerves are situated in the middle portion of the cerebral cortex and in the posterior part of the cortex of the anterior lobe. Third; Each cortical centre probably consists of two parts, a smaller one, in which the peripheral nerve has its final termination, and in which take place those mole cular changes which correspond to simple sensation, and a larger one, in which take place those molecular changes which correspond to the mental processes of memory and comparison, and which together constitute complete perception and recognition. Fourth; Each motor cortical centre probably consists of two parts, a smaller one, in which the peripheral motor nerve has its origin, and in which take place those molecular changes which correspond to the action of the will in originating voluntary movements, and a larger part, in which take place those molecular changes which correspond to the memories of coordinated muscular innervation, which are factors in the production of voluntary movements. Fifth; The optic fibres from the right upper quadrant of each retina terminate in the lower half of the right cuneus. Sixth; The optic fibres from the right lower quadrant of each retina terminate in the adjacent part of the right medial occipito-temporal convolution. Seventh; The lower half of the cuneus and the adjacent part of the medial occipito-temporal convolution is the point of termination of the optic fibres from homonymous halves of the retina the right half of each retina

being represented in the right occipital lobe and the left half in the left lobe. Eighth; Functional activity of the cortex of the median surface of the occipital lobe is necessary for simple visual sensation. Ninth; Functional activity of the cortex of the convex surface of the occipital lobe is necessary for full visual perception and recognition and for the production of visual memories. Tenth; The temporal lobe is the cortical centre for hearing, and the complete destruction of the temporal lobe or of the auditory fibres running to it causes complete deafness of the opposite ear. Eleventh; Functional activity of the cortex of the left superior temporal convolution is necessary for the perception and recognition of spoken words and for the production of the memory of these words, disease of these parts causing inability to understand spoken words, and sensory aphasia. Twelfth; Functional activity of the cortex of the left angular convolution is neceesary for the production of memories of the appearance of written or printed words, lesions of it causing alexia and agraphia. Thirteenth; Only in virtue of the fact that on its functional activity depends the production of the memories of the appearance of written or printed words, can the angular convolution be considered as forming part of the visual centre Fourteenth; The cortical centre of the leg includes the paracentral lobule and the upper third of the two central convolutions and the greater part of the superior parietal lobule. Fifteenth; The cortical centre for the arm includes the posterior part of the superior frontal convolution, the middle third of the two central convolutions and the anterior part of the inferior parietal lobule. Sixteenth; The cortical centre for the face includes the lower third of the two central convolutions especially the anterior one. Seventeenth; In the anterior part of the cortical centre for the arm originate the fibres for this limb, and lesions of this part cause absolute paralysis of the arm. The same thing is probably true in the case of the cortical centres for the leg and face. Eighteenth; In the posterior part of the cortical centre. for the arm take place those molecular changes which are necessary for the production of memories of co-ordinated muscular innervation. The same thing is probably true in the case of the cortical centres for the face and leg. Nineteenth; No sharp line can be drawn between the motor centres of the leg, arm and face of the same side, and it is very possible that in each centre all three parts may be more or less completely represented. Twentieth; The cor

tical centres for muscular and cutaneous sensibility are the same as those for motility, and probably extend backward and beyond the latter over the parietal lobe also. Twenty-first; Tumors or other irritative lesions situated in the non-motor region of the cerebral hemispheres, can cause general convulsion associated with loss of consciousness.

During the past year some interesting investigations have been published in regard to special nerve physiology, but the length of this paper will not admit of their recital. Certain novel investigations have been made by Luys in regard to the movements of the brain within the cranival cavity which are worthy of notice. In 1884 Luys attempted to prove by means or experiments upon the cadaver that the brain being smaller than the cranial cavity and the space between the brain and the bony covering thus formed being filled with fluid, the brain could accomplish certain sliding movements similar to the movements of the foetus in the amniotic fluid. A change in the position of the head would therefore produce a displacement of the brain. In lying upon the back the brain loses its point of contact with the skull in front. The result is similar when the head rests upon the frontal region; then the back part of the brain leaves the skull behind. If this theory is correct the brain moves in the cranium when the head is moved. The theory explains the physiological action of the arachnoid; its function probably being to facilitate these movements. It was objected to the theory of Luys that he had performed his experiments upon subjects that had been subjected to traumatism. He has obviated this objection by freezing the head while the body was kept either in a horizontal or vertical position, and then made sections of the skull and brain. Tracings of these sections were made through plates of unpolished glass The first tracing shows a horizontal section of the skull and brain of the subject placed in a horizontal position. The second shows a vertical section of a subject that had been placed vertically. The results practically confirmed his previous experiments. The space left by the movement of the brain, between it and the skull corresponded in all cases to the position of the subject, and in these spaces was found frozen fluid. This practically demonstrates the correctness of his theory that the brain does move within the cranium.

ARTICLE XI.

THE STUDY OF BACTERIA.

A LECTURE BY IROF. E. A. BIRGE OF THE STATE UNIVERSITY.

NOTE BY THE SECRETARY.-Prof. Birge's lecture was wholly without the aid of manuscript and was illustrated by the exhibition of a large number of specimens of bacterial growth, showing various kinds and methods of culture employed in Bacterialogical Laboratories. The following report of the lecture is from the stenographer's notes and concerning it Prof. Birge desires it to be said that it "does not pretend to be a presentation of the subject of Bacteriology. It was merely an accompaniment to the exhibition of a series of culture-tubes and other preparations."

MR. PRESIDENT AND MEMBERS OF THE SOCIETY:

About eight years ago Dr. H. Charlton Bastian, of England, announced in one of the journals of that country that as far as he could then see he had made the theory of spontaneous generation exceedingly probable. He said that by a series of experiments extending at that time over some six or seven years, he had demonstrated to his own satisfaction that from certain fluids containing animal or vegetable matter, and in which, according to his ideas, all germs of lite had been destroyed, there had developed certain living animalcules. Over this statement there arose immediately an active dispute, in which, perhaps, Professor Tyndall played the largest part upon the side of the opponents of spontaneous generation.

I need not here go into his long and brilliant series of experiments; but it may suffice to recall to your minds the facts which he succeeded in proving, viz: That in fluids which had been boiled a certain number of times there was no development of animal or vegetable life of any kind unless these fluids had been contaminated by exposure to the air; he found, indeed, that in those fluids kept in unsealed tubes and exposed to air in which all germs had been

destroyed there was no development of life. We may say, then, that in the years 1876-8, or about that time, the theory of spontaneous generation was finally settled as a practical question after some 150 years or more of debate. It seems like recalling ancient history to go back to those days. The development of those departments of science which rest upon the establishment of the doctrine that every living being came from another living being, has been so rapid and extended that one is surprised when he looks back at the debate which preceded this revelation of science and finds that the whole thing occurred only eight or nine years ago.

We have, to-day, based upon the assumption of the impossibility of spontaneous generation, a new department of science, with its laboratories, with its elaborate apparatus of various kinds, with its professors and with its own periodicals devoted exclusively to its own science. That science, as you well know, is the science of bacteriology.

And while the scientific benefits resulting from the establishment of this truth have been so great, not less rapid and not less important, or rather far more important have been the practical benefits which have arisen. You know far better than I do the enormous impetus that has been given to surgery by the discovery and introduction of the antiseptic or aseptic methods of treatment. No discovery in the realms of surgery, I suppose, unless it be that of anæsthetics, can at all compare in the advantages to mankind with the discovery of the benefits resulting from this method of treatment. In medicine not so much has been done in a practical way, and yet these theories of bacteriology have given to us many new ideas as to the cause of disease and perhaps are now beginning to give us some hints as to new and improved methods of cure. All these things you know far better than I, who have no practical connection with the study of medicine. But since it has been my privilege to be in charge a small bacteriological laboratory for the last year or two, I thought it might not be uninteresting to you to learn something of the method of working in these laboratories and to see specimens of the various cultures and specimens illustrating the various methods of work in such laboratories.

Hardly a number of any medical journal can be taken up without finding described some method of investigating a certain bacillus, or some article detailing discoveries made in one direction or another

« AnteriorContinuar »