The Journal of Comparative Neurology and Psychology (Continuing the Journal of Comparative Neurology) J. MARK BALDWIN, Johns Hopkins University 8. I. FRANZ, McLean Hospital, Waverley, Mass. S. J. HOLMES, University of Michigan B. F. KINGSBURY, Cornell University C. LLOYD MORGAN, University College, Bristol Published bi-monthly DENISON UNIVERSITY, GRANVILLE, OHIO A Monthly Journal Devoted to the Natural Sciences Since its foundation in 1867 by four of the pupils of Louis Agassiz, THE AMERICAN NATURALIST has been a representative American magazine of Natural History and has played an important part in the advancement of science in this country. The journal aims to present to its readers the leading facts and discoveries in the fields of Anthropology, General Biology, Zoology, Botany, Paleontology, Geology, and Mineralogy, and the various subdivisions of those subjects. Annual Subscription, $4.00 net, in advance. Single Copies, H. KÜNDIG, Editeur, II, Corraterie, GENÈVE. Archives de Th. Flournoy Dr en médecine. Psychologie PUBLIÉES PAR Prof. de Psychologie expérim. Ed. Claparède Dr en médecine. à la Faculté des Sciences de l'Université de Genève. Les Archives de Psychologie paraissent à époque indéterminée. Chaque fascicule se vend séparément et le prix en est fixé suivant sa grosseur et le nombre des figures. On peut toutefois souscrire d'avance au prix de 15 francs pour un volume (d'au moins 400 pages); avec le dernier fascicule du volume, les souscripteurs reçoivent le titre et les tables des matières.-Les fascicules sont envoyés franco de port aux souscripteurs. Tome ler, vol. broché de 424 pages et 57 figures 15 fr. Tome IV, (En cours de publication) Aux nouveaux souscripteurs du tome IV, les tomes Ier à III sont laissés 15" au prix, de 39 fr. (frais de port compris). Comparative Neurology and Psychology Volume XIV 1904 Number 5 RETROGRADE DEGENERATION IN THE CORPUS CALLOSUM OF THE WHITE RAT. By S. WALTER RANSON. (From the Neurological Laboratory of the University of Chicago and the Anatomical Laboratory of St. Louis University.) With Plate VII. SUMMARY OF THE LITERATURE. It was maintained by WALLER (6) and those who immediately followed him that the end of the nerve fiber attached to the cell body did not degenerate as the result of section of the fiber. Evidence has, however, been steadily accumulating to show that this view is incorrect. The facts bearing on this point have been brought together by FLEMING (1), KLIPPEL and DuRANTE (2), and van Gehuchten (4). These authors review the literature in great detail; but only the briefest summary will be given here, and this will be based chiefly on the excellent review by VAN GEHUCHTEN. The first observations not in harmony with the law of WALLER were made upon cases of long standing amputation. Atrophy of the ventral and dorsal root fibers and of the part of the spinal cord associated with the nerves of the amputated limb has been found in these cases. (DICKINSON, '68, Vulpian, '68, HAYEM and GILBERT, '84, MARINESCO, '92, and others). Experimental amputations of the limbs of animals, involving section of the peripheral nerves, have confirmed these observations, (VULPIAN, '69 and HAYEM, '73), and shown the presence of fibers with fragmented myelin in the central ends of the cut nerves. Degenerating fibers were also found in the ventral and dorsal nerve roots and in the dorsal fasciculi of the cord. (DARKSCHEWITSCH, '92 and MOSCHAEW, '93). The second group of observations opposed to the statement formulated by WALLER has been derived from experiments intended to locate the nuclei of origin of the motor nerves. The tearing out of motor nerves is followed by atrophy or disappearance of their intramedullary roots and nuclei of origin. (Literature summarized by FOREL, '87.) A true degeneration of the central ends of these fibers can be demonstrated by the method of MARCHI (BREGMANN, 92, DARKSCHEWITSCH, '92). In the central nervous system a retrograde or cellulipetal degeneration has been observed in seven localities. A descending degeneration has been seen in the optic radiation after excision of its terminal ramifications in the occipital cortex (VON MONAKOW, '84, MOELI, '93) and in the medial lemniscus after injury to the central gyri (VON MONAKOW, '85, GREIWE, '94, KLIPPEL and DURANTE, '95). The retrograde degeneration in these tracts differs in some cases histologically from WALLERIAN degeneration, the axis cylinder remaining intact while the myelin sheath disappears, although in most cases it resembles true secondary degeneration very closely. Often this cellulipetal degeneration is very extensive, involving the majority of the fibers of the tract. For these reasons, the downward degeneration in the optic radiation and in the lemniscus cannot be adduced as evidence for a double pathway. Similar observations have been made on the pyramidal tract, which in certain cases has degenerated cephalad after a transverse lesion of the spinal cord (WILLAMSON, '93, RAYMOND, '94). VAN GEHUCHTEN has shown that degeneration of the proximal part of injured nerve fibers may occur in the middle cercbellar peduncle, in the fibers passing from the nucleus ruber to the lateral fasciculus of the spinal cord, in the fibers passing from the nucleus of DEITERS to the anterior fasciculus of the cord, and in those from the cells of the formatio reticularis of the pons and medulla to the antero-lateral fasciculus of the cord. That retrograde degeneration occurs in these tracts and not merely the WALLERIAN degeneration of a second pathway, is supported by the facts that the changes in question do not ap pear until fifteen days after WALLERIAN degeneration has begun. and that the cells of origin of these tracts disappear. OBSERVATIONS ON THE WHITE RAT. Introduction and Summary. In a previous paper the writer (3) called attention to the complete degeneration of the splenium of the corpus callosum in a young rat after deep incision of the occipital lobe, and reference was made to a similar observation by VON GUDDEN (5). If this degeneration had occurred according to WALLER'S law, about half the normal number of fibers should have been present on each side of the lesion. But in this case all the fibers had disappeared. This means that the fibers underwent serious alterations in both directions from the point of injury. This observation taken by itself only shows the absence of the myelin sheath in the proximal portion of the injured fiber, as no stains were used which would demonstrate the presence or absence of naked axis cylinders. Since there were no medullated fibers in the corpus callosum at the time of the operation the absence of myelin might be interpreted as due to an arrest of development. But further observations made on older rats have shown that a true degeneration closely resembling the WALLERIAN type may occur in the proximal portions of severed fibers. The chief difference between the changes in the proximal and the distal portions is that the latter pass more rapidly through the stages of fragmentation, solution and absorption, these changes affecting the whole extent of the severed portion at the same time; while in the proximal portions the changes. occur somewhat later and may involve only the part of the fiber nearest the point of injury. Thus forty-five days after a wound is made in the medullated corpus callosum of young rats (21 to 70 days of age) the ordinary WALLERIAN degeneration has run its full course and the resulting debris is entirely absorbed. But at this time fragmentation of myelin may be distinctly seen in the proximal portions of the severed fibers, affecting especially the part in the vicinity of the lesion. |