Studien über das Central Nerven-System der Wirbelthiere

Abstract

DR. LUDWIG STIEDA is already well-known for his admirable papers on the central nervous system of osseous fishes, birds, and some mammals. The present work embraces a description of the central nervous system of the frog, rabbit, dog, cat, mole, and mouse; an account of the course of the fibres in the spinal cord of Vertebrata generally; a comparison of the brain of the various classes of Vertebrata with that of man, and finally, a comparison of the cerebral with the spinal nerves. Of the description of the brain and spinal cord of the several mammals mentioned above we need say nothing here, except to remark that the account is full and carefully drawn up; the minutest structure of the several parts being given as well as their coarser anatomical features. In regard to the brain of the frog, the parts of which have received such different names, Dr. Stieda gives the following description of the organ as it appears, when viewed from the upper surface. The cerebrum presents the following parts in successive order:—1, the medulla oblongata; 2, the cerebellum; 3, the lobus opticus, with its median furrow; 4, the lobus ventriculi tertii (thalami optici of authors); 5, the lobi hemisphærici, each of which terminates anteriorly in a knob constituting the tuberculum olfactorium. On the under surface of the brain there appear successively from before backwards:—(1) the bases of the lobi hemisphsphærici; (2) the chiasma of the optic nerves, which last proceed from (3) the lobus opticus, and between which is situated (4) the hypophysis cerebri, and behind this (5) the base of the medulla oblongata, M. Stieda then gives a full description of these parts, and of the various cerebral nerves in the frog. To this succeeds a very good general view or résumé of the anatomy of the brain in mammals. We may draw attention to some remarks made in the section where a comparison is made between the brain of man and that of the several classes of Vertebrata. It may be premised that little difficulty is experienced in discovering the homologous parts of the central nervous system of man and the more highly organised mammals. In the birds, however, there are several parts that are difficult to decipher; whilst in Amphibia, and still more in fishes, the nature of the several parts has given rise to much discrepancy of opinion between different observers. Dr. Stieda refers to his former work for the brain of fishes. In regard to Amphibia and reptiles, he considers that the lobi hemisphærici, or anterior lobes, being hollow, and containing a ventricle, are clearly the analogues of the cerebral hemispheres of man. The azygous portion of the central cavity, between the posterior parts of the hemispherical lobes (or ventriculus communis) in the frog, is the indication of the primordial single cavity of the first cerebral vesicle, and consequently establishes the transitional stage between the osseous fishes and the higher Vertebrata. The succeeding segment constituting the lobus ventriculitertii, (or Zwischenhirn) corresponds in its upper part to the thalami optici; in its lower to the tuber cinereum and lamina cinerea. The third segment, or lobus opticus, agrees exactly with that of fishes, both in its external and internal relations, whilst reptiles exhibit the intermediate type between fishes and birds. Of the nature of the cerebellum there can be no doubt. In regard to birds, he observes, that the great club-like segment of the cerebrum of birds corresponds to the hemisphere of man, the bodies enclosed in them to the corpora striata, the radiated septum to the septum pellucidum. He considers the existence of parts analogous to the corpus callosum and fornix of man to be doubtful. The succeeding segment corresponds to the optic thalami; the large spheroidal body of the lobus opticus to the corpora quadrigemina. Two plates accompany the treatise, which are devoted to the histology of the parts described.

Studien über das Central Nerven-System der Wirbelthiere.

Von Dr. Ludwig Stieda, Prosector in Dorpat. (London: Williams & Norgate.)