CONTENTS:

Professor E. Hering introduced the method of defining colors by data of measurement derived from sensations. He thus became the founder of a new conception in Optics which in many respects promises to give more correct and better explanations not only of the physiology of sight but also of the theory of colors; his views collide however in some important points with the views of the old school, the leader of which is Professor Helmholtz of Berlin. The first article of the present number of this magazine treats of one of these problems, and the author, Professor Helmholtz, believes that the results of his experiments do not show a gradation of the perceptibility of differences which would justify Professor Hering's theory of colors. Professor Helmholtz applies Fechner's law concerning the measurement of perceptible differences to color-sensations. For the experiments he has made, a wheel was employed (after the method of Maxwell) into which slips of colored paper of various breadth could be inserted. He found by this "photometrical" method that "the effect of an additional color upon the luminosity is effectually weakened by the amount of the same color present in the whole mixture…. Equal small amounts of the quantity of light produce the smaller effects the larger the quantities of the same light are in the whole field." We pass by other results of Professor Helmholtz's experiments, for it takes a specialist to go over his calculations and tables; and the investigation has by no means been brought to a final conclusion. "If the strong deviation is not based upon an error," Professor Helmholtz says, "quite another and a different hypothesis would come into question, viz, whether it may not always be the clearest sensation which has effect and that which remains below the threshold does not come into consideration." The revision of his "Handbuch der physiologischen Optik" has been the occasion for these experiments of Professor Helmholtz.

Professor Gaule of Zurich propounds a most interesting theory about the development of the trophic functions and the chemical actions of the nervous system. He starts with the idea that the processes of the nervous system are in accord with the law of the conservation of energy. Du Bois Reymond's remark that love and hatred, pleasure and pain would remain unexplained even if all the changes that take place in the arrangement of atoms in our nerves were known and mathematically computable, has made a deep impression because it expresses the disparity of our definitions of atoms on the one side and feelings on the other. Yet our atomistic theory is not final; it is only an auxiliary conception which will simplify thought so long as the present method of considering phenomena from a chemical or physical and geometrical standpoint is retained. As soon as we create a common auxiliary conception to comprise all these sciences, we shall have to broaden our definitions. Taking this position as his philosophical basis, Professor Gaule attempts to consider nervous processes as reflex actions, the latter being clearly conceivable as subject to the law of the conservation of energy. Living beings appear as complexes of forces developed from the chemical actions taking place in their organisms. Through a saturation of the affinities of their carbon and hydrogen atoms with oxygen their potential energy is changed into kinetic energy. The latter is used in many various ways, partly for building up more complex molecules, partly for again storing potential energy, and partly,—and this is a predominant process in animal organisms,—for setting forces free which will serve as a source of their activity. It is such a source of activity which the impressions of the outside world affect. The impression is called Reiz or irritation, and the irritation has often been compared to the fuse or the spark igniting a powder-mine. We must however bear in mind that the organism is unlike the powder-mine, not at rest but in constant action and the irritation does not properly speaking evoke a reflex but it only modifies the action taking place. All this is generally conceded by the physiologist. Professor Gaule then proceeds to explain his idea of the nervous development. The cells of the epithelium in the skin perform a peculiar process, called in German Verhornung; they turn into horn (keratine) by the protoplasm's losing its albuminoids. The process does not take place in one cell but in several layers of cells and represents like all actions a play of forces, raising the more keratinised strata from the basal membrane to the surface. The keratinising however is, according to Gaule, only the less important surface-phenomenon of another peculiar process which is directed toward the interior of the organism. An excretion takes place forming extremely fine threads around the cells which pass through the pores of the basal membrane (a fact proved by Caninis and Fraenkel) where they form a plexus. Out of the net-like meshes of these plexuses grow increasingly strong filaments which form the trunks of the nerves. These views agree very well with the observations of Professor His on the fœtal development of the nerves. Professor His has indubitably proved that the olfactory nerve for instance does not grow out of but into the hemispheres. The direction of the nervous growth is the same as the direction of their function. Many of the sensory nerves have been proven to, and it is probable that all of them do grow from the periphery into the central organ. Hensen in opposition to this has proposed the theory of an original connection between the peripheral root of the nerve and the central organ; yet whatever side of the controversy may be found in the end to be correct, the result does not much affect Professor Gaule's theory, that the ends of the nerves represent the roots from which they grow and every special irritation must specially affect the secretion which forms the nerve. Having been rather explicit in the basal ideas of Professor Gaule's proposition we can now be brief. The axis-cylinder of the nervous fibre corresponds to the secretion of the nervous root; around it is found the marrow-sheath, a tube of absorbing cells containing, also as proved by Ruehne, a net of neuro-keratine; this neuro-keratine again absorbs the axis-cylinder. To the question Why does not the axis-cylinder disappear? Professor Gaule answers, Because it is constantly renewed. Thus we have a constant flow in the nervous substance, an exchange of materials, an absorption, a secretion, and re-absorption; and in this way it can be, a progress of chemical action conditioning the vertical direction of the nerves upon their plexuses and also the form of the marrow-sheath which appears like craters, one inserted within the other and filed upon the axis-cylinder. Professor Gaule proposes no definite opinion as to the development of the motor nerves; he makes some suggestions which need however further explanation and demonstration. He has apparently not yet finished his investigations and we may expect to hear again from him.

E. Raehlmann, Professor Of Ophthalmology at Dorpat, presents a résumé of his experiences as to the visual development of persons blind from birth to whom by a successful operation sight had been restored. We confine ourselves to a few quotations. "Four weeks after the operation of the right eye and a fortnight after that of the left, on April 28th, the first experiments were made on Johann Rubens. April 30th, patient moved his head more than his eyes. He declared he saw perfectly; yet he was unable to recognise any object except his drinking mug, which on the previous day he had felt with his fingers. Also his shoe was not recognised until he had touched it. May 4th, patient could see that a wooden ball differed from a wooden cube, both being of the same color, but was unable to tell that one was round, the other square. Nor could he distinguish the ball from a disc. After much handling the objects he learned to recognise by sight the roundness of the ball and the squareness of the cube, but he remained unable to distinguish the ball from the disc. He learned quickly to grasp objects in the median line of his eyes but had great difficulty in finding them with his hand when placed at an angle before him.

"May 23d, a glass is again presented to the patient; he sees his picture; noticing the frame, he declares the glass to be a picture. (A picture had been presented to him repeatedly.) Now a second face is shown to him in the glass by the side of his own. Patient becomes greatly bewildered, declaring the picture to be familiar to him. Being asked whether it is that of the Professor, he denies the fact, because the Professor stood beside him. Looking over his shoulder he notices the Professor, and seeing him twice he is confounded…. Patient is left alone and remains almost half an hour before the glass. He moves his arm constantly up and down, observing with a smile how the picture in the glass makes the same movements. Requested to touch his nose, he first grasps into the glass, then behind the glass, repeating this several times. His hand then is put on his nose. Now he laughs and touches the several parts of his face, constantly observing the motions of his hand in the glass."

Most instructive cases of diseases of mind are those in which patients cannot help having and obeying certain ideas which are not, however, hallucinations. Dr. Hack Tuke in the fourth article of this number says: "I was consulted once in the case of a lady, the most important symptom of whose disease was that she had to count up to a certain number before doing the most trivial thing; when she turned at night in bed from one side to the other, or when she took out her watch, or in the morning before she rose; when she went downstairs to breakfast, she would suddenly stop on one of the steps and count; at the breakfast table when about to take the tea-pot before touching its handle"; etc. (Arithmomania). Another case. "A young law-student who had distinguished himself at school, one day read the English sentence 'it was not compatible' and shortly after that he found the sentence, 'I like it not' in German. It struck him that the negative in the one case was placed before and in the other after the word negatived, and he commenced to ponder on negations in general. It became an all-important and all-absorbing problem to him. It kept him from work. For some time he proposed questions to himself like: Why do we not have cold blood like some other animals? etc. He is at present in great danger of becoming undecisive and wavering in his actions, for his passion of ruminating on his problem of negatives weakens his will and threatens to destroy his energy." (Folie du doute.) Esquirol calls cases of Zwangsvorstellungen, in which a patient otherwise healthy is forced to pursue a certain trivial thought, "monomanie raisonnante"; Professor Ball, "intellectual impulses." Although hereditary influences most likely play an important part in this disease they seem to originate in emotions, and Régis for this reason calls them "délire émotif," stating that their ultimate cause must be sought in a diseased state of the ganglionic system of the intestines. Dr. Tuke favors Charcot's term "onomatomanie." The disease is a Wortbesessenheit, a word-mania. Certain expressions or phrases are pressing heavily upon the patient's consciousness so as to force him irresistibly to think them or to pronounce them again and again. Not all cases can be classified under word-mania, but such cases as doubt-mania (Zweifelsucht) or arithmomania are akin to it. Dr. Tuke's advice is not to fight the disease but to teach the patient to ignore it, to treat it as trivial, for the diseased ideas derive new strength from the opposition made to them.

Professor E. Mach explains Weber's discovery that "if a tuning fork is placed upon the head of a person, one ear being shut, the sound is heard and located in the shut ear," in the following way: The sound passes through the bones of the cranium to the labyrinth of the ear and thence out of the ear into the air, thus taking the inverse direction of other sounds we hear. If the flow in one ear be stopped, the sound-waves are reflected and the drum vibrates stronger. Hence the tone will be heard more plainly in the shut ear and will be located there. Professor Schaefer in the last article of this number describes an experiment in the same line, which in another way—the transmission of sound through air waves being excluded—proves the intercranial conductibility of very weak sounds from ear to ear. (Hamburg and Leipsic: L. Voss.)

SCHRIFTEN DER GESELLSCHAFT FUER PSYCHOLOGISCHE FORSCHUNG. No. 1.

LITTERATURBERICHT.