446 Proceedings of Poycd Society of Edinburgh. [sess. 
few inches from the other ear. A fine probe was then passed 
into the meatus, and the centre of the tympanic membrane, with 
the handle of the hammer, was pushed gently inwards, not 
sufficiently, of course, to cause pain. According to the state- 
ment of the subject the sound of the fork was then heard 
considerably loader and more localised in the ear opposite which 
the fork was held. Thinking that this might be due to an 
instinctive movement of the head away from the ear which was 
being touched, and hence nearer to the tuning-fork, the experi- 
ment was repeated, with this difference : the fork was held 
vibrating opposite the end of an india-rubber tube of some length, 
the other end of which was inserted into the ear ; thus move- 
ments of the head would not affect the distance of the ear from 
the source of sound. The result was the same ; the sound was 
heard louder by one ear when the hammer of the opposite ear 
was pressed gently inwards. 
Being surprised at the result of these experiments, a simpler 
and coarser one was tried. Holding the fork in one hand 
opposite one ear, and estimating its intensity, the other ear was 
then closed by the finger ; again the sound was heard louder in 
the one ear when the opposite one was closed by pressing the 
finger into the meatus. According to the statement of the 
subject experimented on, however, the difference was not so 
pronounced as in the case with the probe. 
The experiment was again repeated on an individual gifted 
with an exceptionally good ear for music ; the result was the 
same. 
Using a watch as a source of sound the same results were 
obtained. 
It appeared to me, therefore, that there existed some reflex, 
hitherto undescribed, between the two ears. The next step was 
to find out the path of that reflex. 
By good fortune I was enabled to try the experiment on an 
individual who had perfect hearing in the right ear, but in whom 
the malleus of the left ear was firmly adherent to the inner wall 
of the tympanum and quite immovable, — the result of suppura- 
tion many years ago. On pressing against this malleus the 
sound of the fork held opposite the good ear was unaffected ; its 
