constantly contain such fibers. The overlapping of the areas of skin supplied by the successive nerves is great. J. E. ANDERSON (Yale) 880. TREVAN, J., and Boock, E., The Effect of Section of the Vagi on the Respiration of the Cat. J. of Physiol., 1922, 56, 331339. The effects of removing the brain of the cat from in front of the anterior colliculi, from a section between the colliculi, and from back of the posterior colliculi, upon respiration are studied. The effects are similar to those produced by very light anesthesia, moderate anesthesia, and deep anesthesia respectively. J. E. ANDERSON (Yale) 881. WILKINSON, G., A Note on the Resonating System in the Cochlea, with Demonstration of a Model, illustrating the Action of a Hitherto Neglected Factor. J. of Physiol., 1922, 56, ii-iv. The writer contends that basilar fibers are differentiated progressively with reference to mass, as well as to length and tension. He describes a model of a portion of the cochlea to demonstrate this factor. J. E. ANDERSON (Yale) 882. HILL, A. V., The Maximum Work and Mechanical Efficiency of Human Muscles and Their Most Economical Speed. J. of Physiol., 1922, 56, 19-41. An instrument is described by means of which the maximum work of human muscles (biceps and brachialis anticus) can be determined. As the mass of the load increases, the maximal work increases also, at first rapidly and then more slowly, tending to reach a definite value equal to the potential energy set free. In a maximal effort the duration of the shortening may be changed by changing the load. The mechanical efficiency of human voluntary movement is discussed. It is shown that there is a certain optimum speed of movement below which the efficiency falls slowly and above which it falls rapidly. The mechanical efficiency of a submaximal effort is always less than that of a maximal effort occupying the same time, and in general the stronger effort is the more efficient. Moreover, the stronger effort has the greater optimum speed. J. E. ANDERSON (Yale) 883. ADRIAN, E. D., and FORBES, A., The All-or-Nothing Response of Sensory Nerve Fibers. J. of Physiol., 1922, 56, 301-329. Hitherto the evidence for the all-or-nothing principle has been obtained almost exclusively on the motor nerve fibers of the frog. This investigation was undertaken to determine whether the relation holds good for afferent as well as for efferent fibers. Impulses set up in the internal saphenous (of the cat) by stimuli of different strength are all equally capable of passing through a narcotized region. When conduction fails for an impulse set up by a weak stimulus it fails also for a strong stimulus. The size of the impulse is therefore independent of the strength of the impulse in the sensory as in the motor fiber. The response of a sensory nerve trunk to a single momentary stimulus may vary in two ways, (a) a strong stimulus will excite more fibers than a weak, and (b) a stimulus which is more than strong enough to excite all the fibers may set up two or more impulses in each fiber. The response to stimuli of different strength was measured in different parts of the arc which is concerned in the flexion reflex of the spinal cat. With reflex stimulation the response of the muscle agrees very closely with that of the afferent nerve, and the gradation seems to depend on (a) the number of nerve fibers stimulated, and (b) the repeated excitation by strong stimuli. When the motor nerve is stimulated the muscle does not give more than a single maximal twitch although the stimulus may be strong enough to give a double response in the nerve. Probably the second impulse has no effect because it reaches the muscle at a time when the latter is still in the absolute refractory state. In the reflex arc, a second impulse due to strong stimulation of the afferent nerve has more chance of affecting the muscle owing to delay at various synapses, etc. A single impulse in the afferent nerve may sometimes evoke two or more impulses in the efferent side of the arc. Whether it does so or not, depends on the condition of the spinal centers. In general the reactions of the reflex arc support the view that the large majority of sensory fibers react according to the all-or-nothing principle. J. E. ANDERSON (Yale) 884. LANGLEY, J. N., The Nerve Fiber Constitution of Peripheral Nerves and of Nerve Roots. J. of Physiol., 1922, 56, 382395. Cutaneous nerves contain many nonmyelinated fibers, the nerves to skeletal muscles contain few. The result in not in favor of the theory that the nonmyelinated fibers have any considerable connection with striated muscle fibers. All anterior roots of the spinal nerves are distinguished from the posterior roots by their containing a large proportions of fibers 13 μ and more in diameter and a relatively small number of fibers of about 7.5 to 11 μ. These differences are most distinct in the lower cervical and lower lumbar regions. The different roots of a nerve fiber vary in constitution; some have many small fibers-up to about 6 μ-and others very few. The arrangement of fibers in bundles depends chiefly upon their number. Very few nonmyelinated fibers and probably none enter the spinal cord in the posterior roots. In the posterior roots of the nerves, the anterior roots of which have no automatic fibers, there are a considerable number of fibers about 5 μ in diameter with a less number about 3 μ in diameter. In the posterior roots of the nerves, the anterior roots of which have autonomic fibers, there is a great increase in the number of 3 μ fibers but not in that of 5 μ class of fibers. It is suggested that the 3 μ fibers in all the posterior roots are the afferent fibers of unstriated muscles and glands. The anterior roots of the nerves which contain autonomic fibers have fibers of the size of the larger preganglionic autonomic fibers (3.8 to 4 μ) but expressively few, if any, of the size of the smaller autonomic fibers (2 to 3 μ). A large factor in determining the size of nerve fibers is the nature of the tissue with which they are connected. J. E. ANDERSON (Yale) 885. HORRAX, G., A Consideration of the Dermal Versus the Epidermal Cholesteatomas Having Their Attachments in the Cerebral Envelopes. Arch. of Neurol. and Psychiatry, 1922, 8, 265-285. The article begins with a discussion of the terminology used in the description of the tumors under discussion, and followed by a historical sketch of these growths, with references to the literature of the subject. Mention is made of the frequency of the two main types, the dermoid and the epidermoid, and of their locations. Two cases from the literature are recited (Bostroem's and Teutschlaender's cases), illustrated by cuts. The three cases from the clinic of Dr. Harvey Cushing, which form the basis of the article, are fully presented, illustrated by gross and histological photographs and roentgenograms. The following summary is appended. "There is group of rare tumors of the intracranial cavity which represent fetal epiblastic inclusions, sometimes of the epidermal layer alone, and sometimes including also the dermal layer. These tumors may or may not contain hair and other tissue elements, according to the depth of the cell layer represented in the inclusion. It is convenient to group all these tumors under the name cholesteatomas, either haircontaining or nonhair-containing. Three examples of the hair-containing variety, or intracranial dermoids, are presented for consideration, and in two of the patients the tumors were removed by operation, in one of them with apparent success." D. A. MACFARLANE (Boston Psychopathic Hospital) 886. HILTON, WM. A., The Nervous System of Phoronida. J. of Comp. Neurol., 1922, 34, 381-389. This interesting, primitive sea animal possesses a crudely centralized nervous system, part of which is separated from the epithelium. Tentacles and body-part have bipolar sense cells, arranged in little groups. Under the influence of an anesthetic the tentacles recover last and are affected first. The body or stem is the last region to suffer from anesthesia. The movements of Phoronis, as studied in the laboratory, are ciliary currents on the tentacles, probably not under nerve control; contractions of the tentacles at least partly under nerve control; contractions of the body stimulated through the surface of the body at almost any point, especially by tactile stimuli just below the tentacles. R. H. WHEELER (Oregon) 887. MOODIE, R. L., On the Endocranial Anatomy of some Oligocene and Pleistocene Mammals. 25 figures. J. of Comp. Neurol., 1922, 34, 343-380. A study of nineteen endocranial casts from the White River beds of South Dakota, ranging from Lower to Middle Oligocene, together with two Pleistocene casts from southern California. Rodentia, Insectivora, Carnivora, Cynoidea and Arteidactyle were represented. There has been little or no cerebral development in rodents since Oligocene times. The Insectivora have retrograded in gross cerebral structure as is shown by a more expansive neopallium in Oligocene forms. Some Carnivora show considerable evolution in the complexity of cerebral pattern and in the greater overhang of the cere brum over the cerebellum. Of interest is the fact that primitive horses had unusually well developed brains compared with other Oligocene Mammalia. R. H. WHEELER (Oregon) 888. Ross, L. S., Cytology of the Large Nerve Cells of the Crayfish (Cambarus). J. of Comp. Neurol., 1922, 34, 37-72. Much of the cytology of nerve cells offers the perplexing problem: Are we observing structures that are present as such in the living organisms or are we observing artefacts brought about by chemical reagents? By means of intravitam staining the experimenter found some evidence of neurofibrillæ in the living cytoplasm of Cambarus nerve cells. Axones were found to originate deep within the cell body by convergings of neurofibrillæ. These minute structures were widely distributed elsewhere in the cytoplasm, almost surrounding the nucleus. No trace was discovered of Nissl bodies in living cells but this fact does not preclude the possibility that the Nissl chemical substance, chromidial, exists in living nerve cells. The author inclines to the view that Nissl bodies, themselves, are artefacts. Mitochrondria were readily demonstrable in cell bodies and along the course of the fibers. No Golgi internal reticular apparatus was found. Trophospongium shows connection with the sheath cells and consisted of delicate filaments penetrating even to the center of some cells. R. H. WHEELER (Oregon) 889. HINES, M., Studies in the Growth and Differentiation of the Telencephalon in Man. The Fissura Hippocampi. J. of Comp. Neurol., 1922, 34, 73-171. This is an elaborate study of eight embryos from 11.8 to 43.0 millimeters in length, together with considerable other material for reference. Differentiation does not follow any logical order and is subject to different rhythms of acceleration in different regions. The developing neopallium apparently acts as a disturbing factor, obscuring phylogenetic order or patterns of growth. Before this disturbance takes place certain features of growth in the fissura hippocampi suggest phylogenetic history. The initial differentiation of the neopallium runs behind the hippocampus but subsequently surpasses the latter. The author found some confirmation of Herrick's |