TRANSACTIONS OF THE SECTIONS. 
87 
the author considers to be dependent on the flat, elongated form of 
the mammary gland. He advances arguments to show the proba¬ 
bility of there being, in fact, a special structure at the oriflce of the 
nipple to prevent loss of milk by any other external pressure than 
that upon the teat or nipple itself. 
Both M. St. Hilaire and Mr. Hunter have assumed that, in con¬ 
sequence of the opposite condition of the nostrils of the mother and 
young during the act of suction, this process can only be performed 
by the young between two respirations. The act of sucking, Mr. Hun¬ 
ter states, must also be different in the Cetacea from that of land 
animals, “ the lungs having, in the former, no connexion with the 
mouth.” On these points the author differs from the eminent autho¬ 
rities quoted, and enters into an examination of the action of the soft 
palate in the functions of breathing and deglutition; from which he 
deduces the conclusion, that the mouth is a separate and distinct 
cavity , capable of increasing or diminishing its capacity, and, conse¬ 
quentlyr, of forming an imperfect vacuum, into which the milk rushes 
in sucking, and from which , when accumulated, it is transferred to 
the oesophagus. It must not be forgotten that the construction of 
the soft palate in the Cetacea is different from that in other animals: 
it is in them in the shape of a muscular partition, with a circular 
aperture surrounded by a sphincter; while the top of the larynx is 
elongated so much upwards that it enters this aperture, and, being 
grasped by the sphincter, communicates with the blow-hole or nos¬ 
tril, leaving the mouth and fauces unaffected by the process of re¬ 
spiration, and still better adapted than in other animals to cany on 
the operation of sucking. 
On the Mechanism of Bruit de Soufflet. By Dr. Corrigan. 
The first part of the paper cqnsisted of an analysis of the various 
theories which had been proposed to account for this sound and its 
varieties, bruit de rape, &c. Laennec supposed it to be produced by 
spasmodic action, but his opinion has been generally abandoned. 
By some the sound has been attributed to increased pressure made by 
narrowing of the heart or arteries,—but it is heard in permanent pa¬ 
tency of the aorta, in the vessels of the pregnant uterus, in aneuris- 
mal dilatation of arteries in varicose tumours, in all which instances 
there is no narrowing;—by others to increased velocity in the motion 
of the blood; but it is not heard in the circulation of the foetus or 
infant, while it is audible in the slower circulation of the mother; 
nor in the quickened pulse of hectic or inflammatory fever, while it 
is audible with a pulse of 70. By others it is attributed to rough¬ 
nesses in the interior of arteries, or irregularities, over which the 
blood, in passing, produces the sound; but it is not heard in the 
healthy heart, the internal surface of which is exceedingly irregular; 
nor is it necessarily present in aneurisms, rough and irregular on 
their inner surface, from shape, or from deposition of fibrine ; the 
sound, on the contrary, being frequently heard when there is no de- 
