Oct. 17, 1878] 



NATURE 



659 



direction, that is, in a direction which the experimenter, judging 

 from his sensation of rotation, concludes to be fixed, then rapidly 

 returns to its original position relatively to the head, again for a 

 short time looks in an apparently fixed direction, and so on. 



Some physiologists have considered there oscillatory move- 

 ments as the cause ; others — and notably Dr, de Cyon — regard 



them as the effect, of the visual vertigo. The latter opinion 

 seems the more reasonable ; and indeed both visual and tactile 

 vertigo seem to be matters of judgment rather than of sensa- 

 tion. When the real rotation stops the experimenter perceives, 

 by his sense of rotation, that his head is turning round ; he feds 

 that his body and the chair on which he sits are at rest rela- 



Fig.l. 



lively to his head ; he j^-^j that external objects are at rest rela- 

 tively to his head ; and he concludes that, as his head is turning 

 round, his body, his chair, and all external objects must be 

 turning round also — his eyes oscillate precisely as they would 

 do if all these imaginary rotations were real. 



Similar oscillatory movements of the eyeballs are described 

 by Dr. de Cyon as resulting from the section or mechanical 

 irritation of the semicircular canals in rabbits, and are by him 

 referred to reflex action dependent on intimate anatomical con- 

 nection between the roots of the nerves of the ampullae and those 

 of the motor nerves of the eye. The points of chief importance 

 noticed by him are : — 



1 . At the moment of irritation the spasm of the muscles of 

 the eyeballs has a tetanic character ; immediately afterwards 

 the oscillations commence, and last for a variable time, depend- 

 ing on the intensity of the irritation, and rarely exceeding half- 

 an-hour. The frequency of the oscillations varies from 20 to 

 1 50 per minute. 



2. The direction of the oscillations depends on the particular 

 canal cut or irritated. Dr. de Cyon describes, somewhat 

 minutely, the direction in each case, but states that he finds it 

 difficult, on account of the peculiar position of the eyes in the 

 rabbit, to give a precise determination of these directions. 

 From his descriptions we can, however, gather, with consider- 

 able probability, that the eyeballs oscillate about an axis perpen- 

 dicular to the plane of the divided or irritated canal. 



3. The oscillation?, caused by the irritation or section of any 

 one canal, cease when the opposite auditory nerve is divided ; 

 new irritations of the canal then produce only tetanic con- 

 tractions. 



The direction of the initial tetanic spasm is given by Dr. de 

 Cyon, and appears to coincide with what we should expect if 

 rotation with the ampulla preceding be supposed to excite the 

 ampullary nerves ; this result leads to the suspicion that we may 

 have misinterpreted the author's account of the initial movement 

 of the head on section of one canal in the pigeon. 



We have now only to state and examine Dr. de Cyon's theory 

 of the function of the canals and of the part which they take in 

 the formation of the idea of space. 



This theory is stated in a very general form, and it is difficult 

 by a single quotation to do fvdl justice to it. We quote, how- 

 ever, two passages in which it is distinctly enunciated, and 

 refer the reader for its full discussion to the thesis itself : — 



" I.es canaux semi-circulaires sont les organes peripheriques 

 du sens de I'espace ; c'est-a-dire que les sensations provoquees par 

 I'excitation des terminaisons nerveuses dans les ampoules de 

 ces canaux servent a former nos notions sur les trois dimensions 

 de I'espace. Les sensations de chaque canal correspondent a 

 une de ces dimensions. 



"A I'aide de ces sensations, il peut se former dans notre 

 cerveau la representation d'un espace ideal sur lequel seront 

 rapportees toutes les perceptions de nos autres sens qui concement 

 la disposition des objets qui nous entourent et la position de notre 

 corps parmi ces objets." — P. 64. 



' ' La disposition des nerf s, dans trois plans perpendiculairs 

 I'un a I'autre, se prete a merveille pour une pareille fonction. 

 Nous pouvons tres bien nous figurer comment les sensations 

 d'etendue, dans trois plans, dont la disposition, chez tous les 

 vertebres, repond exactement aux trois co-ordonnees de I'espace, 



peuvent etre utilisees par notre intelligence pour la construction 

 d'une notion de I'espace. 



" Je dirais plus : aucun autre sens ne preseiite une relation aussi 

 facile a saisir entre la representai ion et la sensation, que le sens 

 d'espace, d'apres ma maniere de voir." — P. 73. 



This is not inconsistent with the kinetic theory as explained 

 above. The difference is that that theory does, and Dr. 

 de Cyon's dees not, explain what the sensations of the canals 

 are and how they contribute to our ideas of direction or orienta- 

 tion in reference to three rectangular axes. 



There are two ways in which we may investigate the action of 

 an organ of sense : — We may examine and compare the infor- 

 mation we obtain by means of the sense under a great variety of 

 conditions ; this is the way in which our knowledge of physio- 

 logical optics has been chiefly obtained : or we may study the 

 effects of injuries of the organ, either occurring naturally or 

 intentionally produced. A detailed theory has, in the case 

 before us, been sooner attained by the first of these ways than 

 by the second. This theory must be tested by experiments 

 carried out in every appropriate way, and, if necessary, must be 

 modified in accordance with their results. We may thus expect 

 to obtain a knowledge of the m.echanism of the sense of orien- 

 tation as complete as that which we have of the mechanism of 

 the sense of sight. Dr. de Cyon's thesis contains the record of 

 a very considerable step in this direction. 



Alex. Crum Brown 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



The President and Fellows of St. John's College, Oxford have 

 just passed the following resolution nem. cctu, : " That indepen- 

 dently of the granting of Fellowships for the assistance of 

 research, the college shall from time to time make money grants 

 for that purpose." The granting of Fellowships alludes to a 

 clause in the new Statutes which has just been drafted, in 

 which a Fellowship is set apart for this purpose. 



Prof. Huxley will lecture at a general meeting of the 

 Working Men's College, Upper Kennington Lane, to be held on 

 the 24th, at 8.30 P.M., to inaugurate the new premises of the 

 CcJlege, near Vauxhall Station, one part of which has been 

 fitted up as a chemical laboratory, with all the appliances 

 needed for the study of practical chemistry. 



The New South Wales correspondent of the Colonies states 

 that, in consideration of the necessity which is now felt for 

 extending the curriculum of Sydney University and augmenting 

 its teaching powers, the Colonial Government have consented to 

 ask Parliament for an additional annual grant of 5,oco/. This 

 will enable the Senate to make the following additions to the 

 present course of study : — (i) Mental philosophy, law, history, 

 and English literature ; {2) all the education necessary for the 

 medical profession ; (3) a complete course of natural philosophy, 

 coupled with mechanics and engineering ; (4) the addition of 

 organic chemistry and metallurgy to the chemical school ; and 

 (5) biology, including animal and vegetable physiology. The 

 Senate will also be in a position to establish a faculty of science, 

 and to confer the degrees of Bachelor and Doctor of Science, 

 and also degrees in medicine, on those who have received their 

 education in Sydney. 



