ii SENSIBILITY OF THE INTEKNAL OKGANS 117 



they received different interpretations, according as the disorders 

 were held to be phenomena of irritation or of deficiency. 



In continuance of Flourens' experiments Goltz (1870) de- 

 scribed certain motor disorders consequent on lesions of the 

 labyrinth, not only in mammals and birds, which exhibit nystag- 

 mus of the head and eyes as described by Flourens, but also 

 in frogs and fishes, which do not present these phenomena, and 

 in invertebrates after removal of the otoliths. The disorders 

 described by Goltz consisted in forced positions taken up by the 

 animals after operation, and uncertain equilibrium in locomotion. 

 The forced positions are specially apparent in fishes, frogs, and in 

 aquatic invertebrates, operated on upon one side only. The un- 

 certainty of locomotion, on the contrary, is more apparent in 

 mammals and birds after bilateral operation. These phenomena 

 bear a strong resemblance to those that result from uni- or bilateral 

 extirpation of the cerebellum, which we have already discussed. 



As showii in Vol. III. p. 463, the phenomena studied by Goltz 

 led him to consider the non-acoustic labyrinth as the seat of the 

 sense of position for the head, on which depends the function of 

 equilibration. The disorders consequent on the lesions of the 

 canal depend, according to Goltz, on the absence or perversion of 

 sensations of the position of the head. He assumes that each 

 ampulla is excited by the gravity of the endolymph contained in 

 the corresponding canal; so that with each active and passive 

 movement of the head, there must, as the canals change their 

 position, be a change of pressure in the endolymph, sufficient to 

 excite one or other of the ampullae. 



Numerous objections were made to this theory. We must here 

 confine ourselves to stating that the disorders of locomotion 

 described by Goltz do not last long ; that there is a stage at which 

 they have not yet disappeared, although the animal's sense of the 

 position of the head is perfect ; that, lastly, the canals may be 

 emptied of all their endolymph, without producing any disorders 

 of equilibration. 



In his early work (1873) v. Cyon, starting from Goltz 5 theory 

 that the semicircular canals are organs whose office it is to give 

 the sensations of the position of the head, held that these sensa- 

 tions are necessary in order to acquire the idea of a tri-dimensional 

 space. He repeated the experiments which Breuer had made a 

 few months before (1872) on the effects of the gravity of the 

 endolymph, as assumed by Goltz, of opening the bony canals, of 

 aspiration of the perilyniph with filter paper, and of compression 

 of the membranous canal by tampons, etc., with the same results 

 as Breuer. Cyon therefore excludes the stimulating action of the 

 gravity of the endolymph, but determined no other physiological 

 stimulus for the canals. He only vaguely states that the canals 

 may be excited by the oscillations of the otoliths and endolymph, 



