508 British Association for the Advancement of Science, 



formed by an enlargement of the excretory ducts, and running the 

 whole length of the organ. 



These statements are admitted by Dr. Jacob ; but he remarks, 

 that there is no proof of any special pressure on the mammary gland 

 arising from its position with reference to the muscles ; and that the 

 only peculiarity in the excretory ducts is the existence of the mam- 

 mary reservoir, in the form of a single cavity, — a circumstance which 

 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 orifice 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- 

 quently, 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 carry on 

 the operation of sucking. 



On the Mechanism of Bruit de Soufflet. By Br. Corrigan. 



The first part of the paper consisted 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- 



