most generalised mammals, Erinaceus and Perameles. It is a very constant and precocious sulcus in all the Carnivora, Ungulata, Edentata, Cetacea, and many Rodents and Galeopithecus. Most writers call it "presylvian" in all these non-Primate orders, but there can be little doubt as to its homology with the orbital sulcus, although, so far as I am aware, such an interpretation has never hitherto been suggested. But it would be strange if this (the most widespread and constant) sulcus of the neopallium should not be represented in the Primates, and there is no other furrow of sufficient constancy in the pararhinal region to represent the presylvian sulcus of other mammals. If moreover we compare such brains as those of Dolichotis (Rodent), Galeopithecus (Insectivore), Bradypus (Edentate), and Phascolomys (Marsuipial) with the Lemur's, it is clear that the "presylvian" sulcus of the former can be represented in the Prosimiæ only by the orbital or the fronto-orbital sulcus. Of these the former is not only by far the more constant of the two sulci, but it is also that which occupies the same position and relationship to the rhinal fissure as the "presylvian." A comparison of Galago and Dolichotis shows this.

If again we compare the behavior of the orbital sulcus in the larger Ungulates (e. g., the camel, horse, and ox) and Carnivores (e. g., the Seals), we shall find that as the hemisphere increases in magnitude (and more especially if at the same time it becomes more microsmatic) the "presylvian" sulcus becomes relegated to a position alongside the anterior rhinal fissure exactly analogous to that occupied by the orbital sulcus in the Gorilla's brain. In man the simple linear orbital sulcus becomes complicated by numerous side branches so as to form triradiate, H-shaped or other patterns; but if a large number of human brains be examined, the orbital sulcus will be found to consist in a very considerable proportion of these cases of a single deep linear sulcus, the apparent branches of which are mere shallow furrows of little importance. Not unfrequently this sulcus joins a small anterior rhinal fissure—thus completing the resemblance to the junction of the "presylvian" sulcus with the rhinal in the Carnivora and others.

The coronal sulcus of the non-Primate mammals may be represented in the inferior frontal and the inferior precentral sulci of Man. One of the earliest sulci to make its appearance in the developing Carnivore and Ungulate brain is the coronal. In the Carnivores it often joins the lateral sulcus, in many Ungulates it is linked to the suprasylvian, in the Pig-family it is united with the intercalary sulcus. In the Primates the so-called sulcus rectus exhibits a similar precocity, and occupies a position not unlike that of the coronal in the Ungulates and the primitive Viverrine Carnivores. It becomes split up in the Cebida and Cercopithecida into two parts, the sulcus rectus (sensu stricto) and the sulcus arcuatus. The former develops into the inferior frontal and the latter into the inferior precentral sulcus.

The problem of the exact interpretation of the central (Rolando's) sulcus presents many difficulties. There can be no doubt whatever as to the homology of the mammalian lateral with the intraparietal sulcus of the Primates, and the interpretation of the ansate as the

almost as

sure. We

a

ramus post-centralis superior is find in the carnivora and the Primates respectively deep and important sulcus bearing the same relations to the ansate and lateral sulci. In the former we call it "crucial" and in the latter "central"; the solution thus naturally suggested is that the central sulcus of the Primates represents the crucial sulcus of the Carnivora. Such a view has often been propounded before, and has in several instances been disregarded for no valid reason. Thus it has been urged (with a singular disregard for the facts of the case) that the crucial sulcus "belongs to the mesial wall," in spite of the patent evidence afforded by the Arctoid Carnivora that when the crucial sulcus becomes dissociated from the intercalary sulcus it often lies wholly on the dorsal surface of hemisphere (see the brain of the Bears, the Glutton, and in fact most of the Arctoidea).

If we study the forms assumed by the crucial sulcus in the large Carnivores (such as the Bears and Seals) and by the central sulcus in the large Apes (Simiida), we cannot fail to be struck with a striking. parallelism, which could only be produced by the operation of similar factors in the two cases. Moreover, the earliest phases of the development of the central sulcus in the Lemurs are similar to the first rudiments of the crucial sulcus in the Viverride.

Physiological evidence (which, however, in such matters is notoriously misleading) does not altogether support such an homology. In the Anthropoidea the central sulcus sharply marks the exact caudal limit of the area of excitable cortex, whereas in the Carnivora (so the physiologists tell us) the crucial sulcus lies in the midst of the excitable area.

If we admit the homology of the central and crucial sulci we shall (by comparison with the behaviour of the latter) find an explanation of many features of the former. According to such an hypothesis a glance at a Bear's brain will at once make intelligible the meaning of the superior genu, the caudal bend in the mesial extremity, and the tendency of the central sulcus in the Anthropoid Apes and Man to extend on to the mesial surface in front of the upturned end of the calloso-marginal sulcus.

In the features of its central sulcus (the relative positions of the genua and the behaviour of the mesial extremity of the sulcus) the Anthropopitheci approach much nearer to Man than does the Orang or any other Ape.'

The human brain is distinguished from those of the Apes by the abundance of sulci between these stable and constant elements.

The superior frontal and especially the middle frontal sulci are much better developed than in the Apes, and innumerable sulci develop in connection with these. The inferior transverse sulcus (so constant

As the result of further investigations since the above was written, I have come to the conclusion that the crucial sulcus represents the dorsal part of the central sulcus and that the ventral part of the latter is formed either from or at the expense of (mechanically) the caudal extremity of the coronal sulcus.

in the Simiidæ and larger Cercopithecida) is longer and deeper; and the diagonal sulcus, rarely or never seen in a well-developed form in the Apes, is now almost constantly present as a deep, extensive sulcus, lying between the anterior ascending limb of the Sylvian and the inferior precentral sulcus.

The parietal area is notably much more variable and much richer in secondary sulci than it is in the Apes.

In the temporo-occipital region the "Affenspalte" of the Apes has disappeared, and the depth and extent of the dorsal end of the parallel, the transverse occipital and lateral occipital sulci are correspondingly increased. The inferior occipital, inferior temporal, occipito-temporal, and collateral sulci are usually all present in a well-developed form. In the Apes the deepening and lengthening of any one of these sulci involved a dwindling of its neighbour-a highly developed occipito-temporal sulcus often led to the abortion of the inferior temporal, the disappearance of the anterior end of the collateral, or the curtailment of the inferior occipital or vice versa; but in the human brain there is room for all these unstable and mutually compensatory sulci to exist in a welldeveloped form side by side.

The expansion of the neopallium has far-reaching effects upon other regions of the nervous system: the fiber systems connected with it become more bulky, the cerebellum becomes larger, its middle peduncle the pons-becomes so broad that it completely covers the trapezoid bodies and extends down to the inferior olives. In innumerable ways the whole nervous system is profoundty influenced and modified in structure as the result, directly or indirectly, of the attainment of the neopallium to the height of its perfection.

Obsessions and Psychasthenia.1

In this new work, which, like its predecessors on hysteria and on fixed ideas, deals with large groups of so-called neuroses, P. JANET brings a number of features under a definite heading, the obsessions, impulsions, manias, folly of doubt, tics, agitations, phobias, mysophobias, anxieties, the feelings of insufficiency, neurasthenia and the modifications of the feelings of reality. The very list of these titles gives us a feeling of the confusion that exists in the use of the terms, and we must be grateful to see a more definite entity, after the pattern of epilepsy and hysteria, bring a new order into these conditions so loosely thrown together with neurasthenia. This specialized group is termed psychasthenia. The analysis of the 325

patients has led JANET to the recognition that all these types depend on a lowering of the "psychological tension." Whereas hysteria shows a complete suppression of certain facts and an exaggeration of others,

1 Dr. PIERRE JANET, Les Obsessions et la Psychasthénie. Vol. I. Felix Alean, Paris, 1903.

the psychasthenia shows in the place of this narrowing down of the field of consciousness a lowering of consciousness in its totality, without any complete and localized gaps of anaethesia, anamnesia, paralysis, and without subconscious and subjective elements, and, therefore, with a feeling of the "incompleteness" or insufficiency which is usually absent in hysteria.

The work is of such fundamental importance that an abstract would be too incomplete to be ventured upon. Suffice it to say, that

it is a work with which all those must be completely familiar who wish to get out of the hazy vagueness still existing concerning the so-called neurotic conditions.

The second volume will contain the clinical material on which this first volume is built.

With special gratification we note that beside the cross-sections of these conditions, that is, the analysis of the symptom-complex at various times, there is also some help offered in the direction of longitudinal sections, that is, the analysis of the course of the disease from a general clinical point of view. The relations to mental disorders are given with some detail, especially the occurrence of melancholia, of paranoic states, mental confusion and hebephrenia.

The book is dedicated to TH. RIBOT, who may well be proud of the work of his pupil.

McMurrich's Embryology.'

ADOLF MEYER.

This book is, as the title indicates, strictly a text-book of human embryology. It is written largely from the comparative point of view and is quite full on the neurological side, these chapters comprising about one-fifth of the volume. The work is an eminently successful manual, the references to comparative embryology and comparative anatomy tiding the reader over many difficult subjects, notably in the nervous system. We note a few points of criticism.

In the subject of histogenesis advantage is taken of the foundation laid down by the so-called zones of His to contrast sharply the histogenesis of motor and sensory roots and centers in both spinal cord and brain. But the author has failed to carry out this method of treatment as far as possible and so has missed the recognition of the important fact that both dorsal and ventral zones are divisible into somatic and splanchnic zones, whose clear understanding sheds so much light on the

The Development of the Human Body. A Manual of Human Embryology. By J. PLAYFAIR MCMURRICH, Ph.D. Philadelphia, P. Blakiston's Son & Co.

1902.

broad morphological plan of the central nervous system. Compare the paper by JOHNSTON on the Functional Divisions of the Central Nervous System in the issue of this Journal for March, 1902.

This failure accounts for the error on p. 408 in homologizing the fasciculus solitarius of the oblongata with the oval bundle and hence with the column of BURDACH of the spinal cord. The components of the peripheral nerves are in a later section correctly given and made excellent use of, and a recognition of the fact that the primary and secondary centers of these components within the brain (especially those of the sensory roots) are likewise clearly differentiated would have shed much additional light on the problems of the functional divisions or zones of the metencephalon.

The differentiation of the ventral plate into somatic and visceral series of nuclei is clearly presented (after His) and the visceral (lateral) series is associated with the branchial muscles and their derivatives. This is the traditional view and the one which the reviewer has adopted in his own studies as his working hypothesis; nevertheless it should be recognized that it is not wholly supported by the published facts, especially in the most recent literature, notably the papers of EDGEWORTH. The whole problem of the embryology of the cranial mesoderm of vertebrates requires a renewed investigation and thorough critical analysis.

In discussing the histogenesis of the ventral spinal roots, these fibers are described according to the now current theories as arising wholly from the neuroblasts of the ventral zones of the spinal cord. In view of the constantly recurring evidence of the end-to-end concatenation of cells in the formation of peripheral nerves, some mention should have been made of the "cellular nerve" of the embryo, even though the hypothesis that it participates in the formation of the definitive nerve fiber were rejected.

On page 433, line 14, is an obvious misprint. The word ventral should be inserted before the word motor.

The excellent discussion of the components of the peripheral nerves I would criticise in only one point; viz. the attempt to rank the olfactory nerve and organ as a member of the acustico-lateralis system. This very doubtful homology seems to be a relic of the errors of BLAUE, who endeavored to show that the "olfactory buds" of some fishes represent organs of the lateral line system which had wandered into the olfactory fossa and there differentiated. The futility of this argument was made clear on embryological grounds by MADRIDMORENO in 1886 and later by myself in 1899 (this Journal, Vol. IX, p.