168 ON THE OIIGAN OF HEARING 
independent of the fragility and delicacy of its structure ; 
and these circumstances may account for its being so often 
found separated, as to have led to the vulgar belief of its 
being a separate body, unconnected with any of the sur- 
rounding parts, and of a petrous nature. 
When the substance is dried, and examined by the rays 
of the sun, the parts appear to great advantage ; the white 
conglomerate particles assume a crystalline appearance of 
the most dazzling brilliancy, which is beautifully contrasted 
with the dark particles, that are of a purple colour. The 
encircling filaments appear like small silvery cords ; but, in 
general, are so shrunk as scarcely to be recognized, and are 
seldom or never seen, unless the portion examined be very 
small. 
When a dark-coloured particle is divided by a fine in- 
strument, a nucleus of white substance is often seen in the 
centre of the particle or globule, of more or less size, ac- 
cording to the age of the animal. We may therefore sup- 
pose, that a deposition of the white-coloured particles takes 
place in the centre, and accumulating, presses upon, and 
so causes the gradual absorption of the surrounding dark 
coloured substance. 
In several preparations now before me, both of the shark 
and skate, there is a beautiful continuation or chain of deli- 
cate minute globules, which arises from the inner edge, and 
middle part of the sabulous body, pierces the gelatinous 
humour, and is united to the fine particles of the substance 
contained in the spherical sac. 
The globules are connected by numerous filaments, simi- 
lar to those of the sabulous body. 
These communicating fibres, and the line of globules, are 
found only in the adult ; and hence one reason why the 
meatus should be more contracted in the adult than in the 
