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EXPLANATION OF THE FIGURES.

PLATE IV.

The following figures are free-hand drawings, using Zeiss Oc. 4 x obj. 1-12. Fig. 1.-Cross-sections of the ventral root nerves of the cat, showing distribution of neurokeratin.

Fig. 2.-Longitudinal section of the ventral root nerves of the dog, showing form of cones.

Fig. 3.-Largely magnified drawing of a single nerve-fiber taken from the preparation used for Fig. 2, showing the meshwork in the cones.

Fig. 4. Same as Fig. 3.

Fig. 5.-Enlarged view of a cross-section of a single nerve-fiber taken from the preparation used for Fig. 1, showing neurokeratin framework.

Fig. 6.

Cross-section of ventral root nerve of human spinal cord. PALWEIGERT. Largely magnified. Showing masses of medullary substance included in neurokeratin framework.

LITERARY NOTICES.

Hearing and Allied Senses in Fishes.'

The moot question whether fishes possess the sense of hearing has been attacked experimentally by PARKER with the result that he gives a definite affirmative answer for some types of teleosts. This report will impress the reader as a particularly clean piece of experimental re'search and the conclusions seem to be free from any reasonable question. The experiments were ingeniously planned, carefully controlled and skilfully performed. The general methods of the research, as well as the conclusions, can be gathered from the author's summary of results, which we quote:

I. Normal Fundulus heteroclitus reacts to the sound waves from a tuning-fork of 128 vibrations per second by movements of the pectoral fins and by an increase in the respiratory rate. It probably also responds to sound waves by caudal fin movements and by general loco

motor movements.

2.

Individuals in which the eighth (auditory) nerves have been cut do not respond to sound waves from the tuning-fork.

3. The absence of responses to sound waves in individuals with severed eighth nerves is not due to the shock of the operation or to other secondary causes, but to the loss of the ear as a sense organ. Fundulus heteroclitus therefore possesses the sense of hearing. 5. The ears in this species are also organs of prime importance in equilibration.

4.

6.

Normal Fundulus heteroclitus swims downward from the top of the water and remains near the bottom when the aquarium in which it is contained is given a slight noiseless motion.

7. Individuals in which the nerves to the lateral-line organs have been cut will swim upward or remain at the top while the aquarium is being gently and noiselessly moved.

8. The lateral-line organs in this species are probably stimulated

1 PARKER, G. H. Hearing and Allied Senses in Fishes. U. S. Fish Commission Bulletin for 1902, Washington, 1903, pp. 45-64.

by a slight mass movement of the water against them. stimulated by sound waves such as stimulate the ears.

They are not

9. Individuals in which the nerves to the lateral-line organs have been cut swim downward and thus escape from regions of surface wave action. They also orient perfectly in swimming against a current. Since surface waves and current action stimulate fishes in which the nerves to the lateral-line organs and to the ears have been cut, these motions must stimulate the general cutaneous nerves (touch).

IO.

The vibrations from a bass-viol string when transmitted to water stimulate the ears and the lateral-line organs of Fundulus. They also stimulate mackerel and menhaden, but not the smooth dog-fish, which responds only when in contact with solid portions of an aquarium subjected to vibrations.

We have another interesting set of observations in Professor TULLBERG'S paper on the Functions of the Labyrinth in Fishes.'

The author operated on various teleosts by cutting the semi-circular canals, removing the large otolith and in various other ways and concludes that the labyrinth is not an organ of equilibrium, or of the static sense or for the maintenance of muscular tone or of the spacial sense in the sense of v. CYON. It is probably to some degree an auditory organ (though he gives no satisfactory proof of this). "Originally and primitively, however, the labyrinth of fishes is a sense organ for the perception of movements of the surrounding water, since currents are apparently perceived by the cristae acusticae of the ampullae, but wave movements probably by the maculae acusticae of the utriculus, the sacculus and the lagena. The central organ for this sense organ is apparently the cerebellum."

That the labyrinth is primarily an organ for the perception of currents or streaming movements of the surrounding medium seems on a priori grounds highly improbable, since the stimulus is one which may easily act upon the skin, lateral-line organs or other superficial sense organs, but only with difficulty on the deep-seated labyrinth. Moreover the experiments cited seem inconclusive. In the first place, the canals were merely cut and the nerve endings were not destroyed. The same applies to the removal of the otolith. In several of these experiments there were forced movements and disturbances of equilibrium which the author has to explain away. In general too the lesions were symmetrical. More radical operations would seem to be

2 TYCHO TULLBERG. Das Labyrinth der Fische, Ein Organ zur Empfindung der Wasserbewegungen. Bihang till K. Svenska Vet.-Akad. Handlingar, Stockholm, Bd. 28, Afd. IV, No. 15, 1903.

necessary before permitting the conclusion that the labyrinth is not concerned in equilibration and the static sense. In experiment 12, designed to show that orientation with reference to water currents is not done by the lateral-line canals, the n. lateralis vagi was cut behind the shoulder girdle, with the result that the operated fishes still oriented themselves with reference to currents like normal fishes. But it should be noted that in this experiment the canals of the head, of far greater extent and importance, were uninjured.

Professor TULLBERG'S experiments are criticised at some length by Dr. PARKER in connection with a brief report upon his own experiments recently published in the American Naturalist.

1

A physiological and morphological classification of all of the cutaneous sense organs of fishes as conceived by the present writer is now in press in the current number of the American Naturalist, and the status of such of these organs as belong to the communis or gustatory system is treated more at length in another place in this issue of this Journal.

Taste Fibers and Their Independence of the Trigeminus.'

C. J. H.

The surgical work and clinical observations upon which this report is based seem to have been more carefully planned and more skilfully wrought out for the solution of the problem of the course of the taste fibers than any of the preceding contributions to this difficult theme. In most of these cases a preliminary test of gustatory sensibility was made before the operation-a most necessary precaution, as the event proved. The patients were whenever possible kept under observation and repeatedly tested for long intervals after the operation. The results in all of the cases furnish a strikingly clear proof of the thesis stated in the title, without the confusion and ambiguity of most previous reports.

In general there is a post-operative transient period of total or partial abolition of taste perception, with a gradual return to the normal gustatory sensibility, but no return of tactile sensibility. He says, "I find it difficult to reconcile my fairly uniform results, that is, uniform in so far as the ultimate preservation of taste is concerned, with the contradictory observations which have been made by so many

" PARKER, G. H. The Sense of Hearing in Fishes. Am. Nat., XXXVII, No. 435, March, 1903.

2 CUSHING, HARVEY. The Taste Fibers and their Independence of the N. Trigeminus. Deductions from Thirteen Cases of Gasserian Ganglion Extirpation. Johns Hopkins Hospital Bull., XIV, No. 144, 145, 1903, pp. 71-78.

others. The only explanation which I can offer is that there may be in a considerable percentage of the cases a temporary diminution in its acuity or a complete abolition of taste as has been intimated above, and that this may have been interpreted under certain circumstances as an evidence of permanent loss of this sense."

The conclusions are: I. That the perception of taste is unaffected on the posterior portion of the tongue and never permanently or completely lost on its anterior two-thirds after removal of the Gasserian ganglion.

2. That the temporary abolition or lessening of the acuity of taste may be found to exist over the anterior and anaesthetic portion of the tongue for some days after the operation.

3. That this temporary loss of function may possibly be occasioned by some interference with chorda transmission brought about by a mechanical or toxic disturbance due to degeneration of the N. lingualis.

4. That a lesion of the trigeminal nerve may be associated with disturbance of taste over the chorda territory without the necessary inference that the nerve is a path for gustatory impulses.

5. That the N. trigeminus in all probability does not convey taste fibers to the brain either from the anterior or posterior portion of the tongue.

This last conclusion, it will be noted, has been reached almost uniformly of late by researchers in three independent lines of work, the morphologists, the embryologists and the comparative anatomists, and it is a source of satisfaction to see the confusing clinical evidence at last brought into harmony with these in so unambiguous a manner.

De Fursac's Psychiatry.'

C. J. H.

Almost every language has had its little compend based on the remarkable changes in psychiatric views, produced by rather a daring but decidedly inspiring reform started by KRAEPELIN. This little book adopts the classification of KRAEPELIN, which is partly etiological, but largely a grouping of the mental diseases according to their outcome. The little book has in some respects an intrinsic value, owing to the attempts at harmonizing current French views with those of the Heidelberg school. The book is dedicated to Professor JOFFROY, and is in a way a semi-official acknowledgement of KRAEPELIN's attitude.

A. M.

1 Manuel de Psychiatrie, by Dr. ROGUES DE FURSAC. Paris, F. Alcan, 1903.

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