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Perhaps the most important result which I have obtained from a long series of isolated injections, has been yielded by injecting the internal auditory artery in man and other mammals; but this artery is so very small that it is quite impossible to introduce into it even the smallest injection tube, so that it is necessary to proceed to inject it in another way.

Place a ligature round the basilar artery, immediately in front of the origin of the internal auditory, just behind which the basilar artery may be easily fitted with an injection tube of tolerable dimensions; the injection being then prevented by the ligature from penetrating far into the basilar artery, must pass along into the auditory branch with all the requisite force. Next inject, in the same subject, the middle meningeal artery, with a differently coloured injection; both these injections must be composed of very fine materials. The investigator will now perceive that the labyrinth is supplied by the auditory artery, while the surrounding substance of the petrous bone is supplied by branches of the meningeal.

I shall not now enter into more details; these I reserve for another occasion; but, I may state that this independence of the circulations of the labyrinth and of the petrous bone, will account for the very interesting observations made by several French surgeons, and proved by many convincing pathological preparations, in my osteological collection, that a caries temporum may corrode away almost the whole of the petrous bone, without destroying the sense of hearing; and that the cochlea of a human ear, together with the vestibulum, may be exfoliated through a like caries, just as if prepared by the skilled hand of the anatomist, because the two having separate and independent circulations, each may preserve its integrity apart for a long time.

I have in my possession a very neat looking cochlea, which was taken out, with a forceps, from the external auditory meatus of an otorrhoic patient by a friend of mine, who is Surgeon to a suburban district in Prague.