2. NERVOUS SYSTEM 10. KRAMER, F., Schussverletzungen peripherer Nerven. 5. Mitteilung Plexus brachialis. Monatss.f. Psychiat. u. Neurol., 1921, 50, 279-301. Psychologisch bemerkenswert ist nur die Tatsache, dass bei manchen Plexuslähmungen mit schweren motorischen Ausfallserscheinungen die Sensibilitätsstörungen zuweilen sehr unbedeutend sind. Th. ZIEHEN (Halle a.S.) II. BOER, S. DE, Die autonome Innervation des Skelettmuskeltonus. Arch. f. d. ges Physiol., 1921, 190, 41-53. Die im Jahre 1913 von de Boer aufgestellte Lehre, dass der Tonus der Skelettmuskeln von sympathischen Nervensystem aus hervorgerufen würde und nicht von den eigentlichen motorischen Nerven des cerebrospinalen Systems, ist von verschiedenen Autoren bekämpft worden. De Boer sucht in der neuen Arbeit nachzuweisen, dass diese Einwände unberechtigt sind. Er stützt sich dabei im Wesentlichen auf seine früheren Versuche. BETHE (Frankfurt a/M.) 12. FRANKE, F., Die Kraftkurve menschlicher Muskeln bei willkürlicher Innervation und die Frage der absoluten Muskelkraft. Arch. f. d. ges. Physiol., 1920, 184, 300-321. Mit einem von Bethe angegebenen Dynamometer wird die maximale Kraft der Armbeugung und Armstreckung im Ellbogengelenk bei verschiedenen Winkelgraden gemessen. Auf Grundlage von Röntgenbildern werden die Hebellängen bestimmt und daraus die Drehmomente und die entsprechenden Kräfte des Trizeps, Bizeps und Brachialis berechnet. Die Kraftkurven der Muskeln fongen hoch an, steigen noch etwas und fallen schnell ab. Ihr Maximum liegt an andrer Stelle als das der äusseren Kraftkurven (Ausgleich durch Drehmomente). Maximale Kraft des Trizeps bis 448 kg, daraus grösste Kraft pro qcm (absolute Kraft) 17-20 kg; entsprechend beim Bizeps 130 kg und 9-12 kg. BETHE (Frankfurt a/M.) 13. STEINHAUSEN, W., Ueber die Latenzzeit des Sartorius in Abhangigkeit von der Stromstärke bei Reizung mit konstantem Strom. Arch. f. d. ges. Physiol., 1921, 187, 26-46. Abstufung der Reizstromstarke durch Mannit-Porsäure-Widerstände oder mit der Elektronenröhre. Die Latenzzeiten nehmen mit dem Wachsen der Stromstarke ab. Die Latenzzeiten als Ordinaten zu dem Stromstärken als Abszissen in ein Coordinatensystem eingetragen geben Curven, welche sich als gegen die Axen verschobene Hyperbeln deuten lassen. Verschiedene Möglichkeiten, wie dieses Hyperbelverhältniss zu Stande kommt, werden erörtert. BETHE (Frankfurt a/M.) 14. PFAHL, Ueber die reziproke Innervation. Arch. f. d. ges. Physiol., 1921, 188, 298-302. Nach Pfahl giebt es eine reziproke Innervation antagonistischer Muskeln, wie sie von Sherrington u.a. bei den Reflexen höherer Tiere gefunden wurde, beim Menschen nicht. Die von Bethe an Sauerbruch-Operierten aufgeschriebenen Curven liessen ein reziprokes Verhältniss im mathematischen Sinne nicht erkennen. (Dass eine Reziprozität im mathematischen Sinne vorläge, ist auch nie behauptet worden.) Pfahl schrieb die Bewegungen der Handbeugung und Streckung an Gesunden und an Patienten mit Nervenverletzungen auf. Er glaubt aus denselben schliessen zu können, dass während der Agonist sich sich zusammenzieht, der Antagonist hemmend eingreift. BETHE (Frankfurt a/M.) 15. MANSFELD, G., Beiträge zur Physiologie der Reizerzeugung. 2. Mitteilung. Darm. 3. Mitteilung. Skelettmuskel. Arch. f. d. ges. Physiol., 1921, 188, 241-246, 247-253. Nach einer früheren Untersuchung (Mansfeld u. Szent-Györgyi, Pflügers Archiv. 184, 236, 1920) wird die Kohlensäure als Ursache (innerer Reiz) des Herzschlages angesehen. Hier wird gezeigt, dass der Darm in Lösungen, welche kohlensäurefrei sind und kohlensäurebindende Alkalien enthalten, seine Bewegungen einstellt. Sie kehren nach längerer Latenz in kohlensäurefreier Ringerlösung (durch selbsterzeugte Kohlensäure) oder sofort in kohlensäure-haltiger Ringerlösung wieder. Die Stillstellung soll nicht auf der Gegenwart freier OH-Ionen beruhen, sondern auf dem Fehlen freier Kohlensäure. Ebenso soll die indirekte Erregung von Muskeln ausbleiben, wenn Kohlensäure fehlt; die direkte Erregung soll aber erhalten bleiben. BETHE (Frankfurt a/M.) 16. DUNN, H. L., The Growth of the Central Nervous System in the Human Fetus as Expressed by Graphic Analysis and Empirical Formula. J. of Comp. Neurol., 1921, 33, 405 492. The material for this elaborate study consisted of 156 human fetuses ranging from 3.1 to 53.6 cm. in total or crown-heel length and were quite evenly distributed between these extremes. By inspection field graphs and preliminary curves of growth were constructed; these were then expressed in terms of empirical formulæ. These values were finally converted from functions of crown-heel length to functions of the age in fetal (lunar) months. Lastly, the relative weights of the various parts of the central nervous system were determined in terms of per cents. of the encephalon. Thus, with the abscissæ representing total body length and the ordinates representing weight and volume in grams (c.c.) the curves of the central nervous system as a whole, the encephalon, cerebral hemispheres, cerebellum, pons and medulla, midbrain, and spinal cord show one type of growth curve which is concave with respect to the ordinate. On the other hand the ratios of diameters and lengths of different parts to total bodily length furnish a straight-line "curve." In all were found four varieties of growth. (1) The cerebral, which is characterized by (a) a steady and relatively slow increase in volume from the second to the beginning of the sixth fetal month and a constant and more rapid increase from this time to birth, and (b) by a steady and constant growth in linear dimensions from the second fetal month to birth. (2) The brain stem and cord type, which shows a much more rapid growth from the second to the end of the fifth fetal month than it does in the last five months of fetal life. (3) The cerebellum type which proceeds very slowly from the second to the end of the fifth fetal month and then increases tremendously from the sixth month to birth. The compound type which represents the combined effect of two or three or all of the above varieties, predominated by the cerebral type. These types of growth may be expressed in terms of empirical formulæ. These formulæ are presented. R. H. WHEELER (Oregon) 17. PING, C., On the Growth of the Largest Nerve Cells in the Superior Cervical Sympathetic Ganglion of the Norway Rat. J. of Comp. Neurol., 1921, 33, 313-338. This is a continuation of the study reported in No. 3 of the same Volume of the Jour. of Comp. Neurol. Certain characteristic differences were found between the wild and domestic species the interpretation of which awaits data from long-continued domestication and inbreeding of Norways. R. H. WHEELER (Oregon) 18. AYERS, H., Vertebrate Cephalogenesis. V. Origin of Jaw Apparatus and Trigeminus Complex-Amphioxus, Ammocætes, Bdellostoma, Callorhynchus. J. of Comp. Neurol., 1921, 33, 339-404 Evidence tends to show that the jaw apparatus is not phylogenetically related to gills as was supposed and that the jaw apparatus is the end organ of the trigeminus. The matter bids fair to remain controversial until evidence from other investigations is at hand, for the reason that the origin of certain muscles and cartilages and their nerve supply is problematical. The author hopes to meet certain of these objections to his view in a forthcoming contribution. R. H. WHEELER (Oregon) 19. DETWILER, S. R., and LAURENS, H., Studies of the Retina. Histogenesis of the Visual Cells in Amblystoma. J. of Comp. Neurol., 1921, 33, 493-508. The phylogenetic relation of cones to rods is a matter of vital importance. A difficulty is found in the fact that in certain animal forms structures resembling cones may be rod-like in their functions. Moreover, variability in the shape of the visual cells has made absolute rod and cone distinction a problem in some cases. Evidence from recent and careful study indicates that in amphibia both the rods and cones are differentiated from primitive, non-specialized cells. In the earlier embryonic stages these cells are cone-like in structure. At the age of 15 days true cones are observable. The results of this study do not bear out Cameron (J. Anat. and Physiol., 1905 and 1911) who regards all of the conical-shaped visual cells in early stages of amphibian development as cones and the latter appearing rods as transformed cones. Differentiated rods are later in appearance than the cones. The progenitors of rods and cones, while cone-like at the outset, possess characteristic features by which they can be divided into the parent cells of each differentiated type; the parent cells of the rods are larger, their nuclei occupy a more external position than that of the cones, and the granular material of their outer segments becomes arranged in lamellæ characteristic of the fully differentiated rod. The ratio of these conical-shaped rod progenitors to that of the cones is approximately the same (four to three) as that of the rod-cone ratio in the fully differentiated retina. R. H. WHEELER (Oregon) 20. LARSELL, O., and MASON, M. L., Experimental degeneration of the vagus nerve and its relation to the nerve terminations in the lung of the rabbit. J. of Comp. Neurol., 1921, 33, 509-516. R. H. WHEELER (Oregon) 3. SENSATION AND PERCEPTION 21. Совв, Р. W., and LORING, M. W., A Method for Measuring Retinal Sensitivity. J. of Exper. Psychol., 1921, 4, 175-197. Experimental conditions consisted of an illuminated screen with a small circular aperture in the center through which was visible a smaller screen of the same degree of illumination. The falls of a gravity drop-frame immediately in back of the main screen gave variable short changes of illumination in the center of the observer's field of vision. Four variable factors were introduced by the use of two sizes of aperture (13.138 and 18.096 sq. mm.) and by the presence or absence of shadows on the main screen. O sat at a distance of 6 m. from the screen. Under these conditions it was found that the average threshold time, reduced to its equivalent with a standard opening, is about 24 sigma. At this threshold the product of the area of stimulus and time of exposure is constant. The effective time for stimulation is not appreciably altered by the presence of shadows on the main screen. The position of the judgment within a whole series, and the time of day in the course of experimentation seem to be of negligible effect upon the results. C. C. PRATT (Clark) 22. JONES, E. S., Improvement in Brightness Discrimination and its Bearing on a Behavioristic Interpretation of Perception. J. of Exper. Psychol., 1921, 4, 198-202. In many current psychological textbooks the nature of perceptual experience is frequently treated without reference to the |