ORGAN OE SMELLING.
Two remarkable instances of anomalous structure in parts connected with the nose occur in the proboscis of the elephant, and the blowing holes of the cetacea The former organ consists of two canals, separated from each other by an inter vening partition. Innumerable muscular fasciculi, running in two directions, occu py the space between these and the in teguments. There are fibres of a trans verse course, passing like radii from the canals to the integuments, and others, which run in a more longitudinal direc tion, but .have their extremities turned inwards. The former extend the trunk, without causing any contraction of the canals ; the latter bend or contract it ; and both tend to bestow on it that won derful mobility which it possesses, in eve ry direction.
The more longitudinal fibres are divid ed at short intervals by tendinous inter sections, which enable the animal to bend any part of the organ, and to give it any requisite degree of curvature. The same structure will confer a power of bending different parts of the trunk in opposite di rections; indeed, there is no kind of cur vature which may not be produced by these longitudinal fibres. These fascicu li occupy the external surface of the or gan. The transverse fibres are not all arranged like radii round the canals ; but some pass across from right to left, and must therefore affect the diameterof those tubes by their action. The whole of these muscular fasciculi are surrounded and connected together by a white, uni form, adipous substance. The transverse ones are not more than a line in thick ness. If the number of these which ap pears on a transverse section be ascer tained, and if those portions of the longi tudinal fasciculi, which pass from one ten don to another, be reckoned as separate muscles (for they must have a separate power of action) the whole trunk will contain about thirty or forty thousand muscles, which will account satisfactorily for the wonderful variety of motions which this admirable organ can execute, and for the great power which it is capa ble of exerting.
The blowing hole of the whale serves as well for respiration as for the rejection of the water which enters with.the food. In consequence of its situation at the top of the head, it is easily elevated beyond the surface of the sea, while the mouth is usually under water.
The opening in the bones of the head is divided into two by a partition of bone; and is furnished with a valve opening outwards. On the side of this open ing are two membranous bags lined with a continuation of the integuments, and opening externally: The water, which the animal wishes to discharge, is thrown into the fauces, as if it were to be swallowed ; but its descent into the stomach is prevented by the contraction of the circular fibres of the esophagus. It therefore elevates the valve placed at the entrance of the blowing-holes, and distends the membranous bag, from which it is forcibly expelled by surrounding muscular fibres.
This apparatus occupies the situation, which in other mammalia is filled by the nose ; which organ, together with the si nuses of the head, the olfactory nerve, &c. is entirely wanting in these animals.