THE ACQUEDUCTS. 449 



of the labyrinth always filled it completely; and that without a 

 sort of waste gate for it on an occasion, the vibration of the 

 stapes would be prevented from putting it in motion, conse- 

 quently, hearing must cease. These canals, the existence of 

 which is sufficiently obvious in many subjects, were, therefore, 

 considered by him as the desired avenues for the discharge of 

 the superabundant fluid, and his theory and descriptions were 

 very generally adopted. Of late years, the investigation of this 

 subject has been renewed by MM. Ribes and Brugnone, and their 

 observations are considered by the French anatomists to have 

 proved conclusively the error into which Cotunnius and others 

 have fallen. 



In regard to % the aqueduct of the vestibule, M. Ribes has found 

 it only in three instances emptying into the vestibule; for most 

 commonly it leads, after a course somewhat tortuous, into the 

 spongy structure of the petrous bone, at the posterior part of 

 the vestibule, and smaller canals diverge from it in different di- 

 rections In the cases where it was connected with the laby- 

 rinth, it was so by several orifices leading into the vestibule, 

 arid into the posterior semicircular canal. He has not found 

 this canal in the foetus, nor till some time after birth, and from 

 his injections he believes that, in all cases, it and its branches 

 are only intended to convey blood vessels throughout the pe- 

 trous bone and to the labyrinth. 



In regard to the supposed aqueduct of the cochlea, M. Ribes 

 has also found it diverging into collateral branches, and occu- 

 pied by blood vessels, which are distributed to the spongy struc- 

 ture of the petrous bone, and to the tympanum, 



In my own researches on this point, on the dried bones, the 

 canals, as described by Cotunnius, were closed at the labyrinth, 

 in the case of subjects advanced in life ;. but, in the middle aged, 

 and in infantile specimens, I have been more successful in 

 tracing them fairly into the labyrinth, and have the prepara- 

 tions in the Wistar Museum, At the same time, I think it 

 much more probable that they only contained blood vessels, 

 and that Cotunnius was in error. Besides these vascular ca- 

 nals, M. Ribes has described some others having the same use* 



