585 ) 



Ada Academic C<es. Leop. Carol. Natura Curiosa Bornue. Vol. 

 XIII. and XIV. 18261828: (On the Blood-vouch of the. 

 Head, and on the Internal Ear of some Hybernaiing Animals.) 

 By Dr. A. G. Otto. 



DR. OTTO'S anatomical inquiries, having for object the investiga- 

 tion of the arrangement of certain parts of the vascular system 

 in hybernating animals, have been attended by the establishment of 

 some singular and unexpected facts. Mangili (Annahs du Museum, 

 x. 463.) had asserted that in some, and perhaps all, hybernants, 

 the internal carotid artery is wanting, the brain being supplied with 

 blood by the vertebral artery only, and in small quantity ; a fact 

 which he supposed to be connected with diminished irritability of 

 the brain, and consequently with the periodical lethargy peculiar to 

 such animals. Saissy, on the other hand, (Recherches sur la Phy- 

 sique des Animaux Hybernans^) states, that in such animals the 

 heart and internal vessels are more than ordinarily capacious, whilst 

 the external vessels are smaller, and the cutaneous nerves larger 

 than in other animals : hence, therefore, that the hybernants are 

 more readily rendered torpid by cold. 



According to Dr. Otto, hybernating animals do not present these 

 peculiarities ; but, on the contrary, have others equally remarkable, 

 though less obvious. The brain is supplied with at least as much 

 blood as in other animals, though the channels through which it 

 passes are differently arranged. The internal carotid appears at 

 first sight to be deficient, the vertebral artery being proportionally 

 very large, uniting with its fellow to form the basilar, which fur- 

 nishes not only the vessels of the posterior part of the brain and the 

 circle of Willis, but also the anterior cerebral, and the ophthalmic 

 arteries. Neither is the internal carotid really wanting, though its 

 course is very peculiar. In the bear, badger, hare, rabbit, and 

 beaver, the vessel passes through the carotic canal ; in the porcu- 

 pine it is the continuation of the trunk of the internal maxillary, 

 and enters the cranium through the foramen lacerum anterius; in 

 the cavy and aguti it is but a lateral branch of the same vessel, and 

 enters the cranium through the foramen ovale. In all the hyher- 

 nants, on the other hand, the internal carotid passes into the cavity 

 of the tympanum by, or near to, the jugular foramen, and, in its 

 course into the cranium, perforates the open ring of the stapes or 

 stirrup-bone of the ear : this structure prevails in bats, hedge-hogs, 

 shrews, moles, lemmings, all mures, myoxi, in the hamster, jerboa, 

 marmot, and squirrel. These are precisely the animals which pass 

 a certain portion of the year in a stale of sopor, the apparent ex- 

 ceptions, as in the Mus genus, probably depending on the more 

 artificial habits of these animals, produced by their intercourse with 

 man. The bear and badger, on the contrary, in which the carotid 

 artery follows the ordinary course, do not really hybernate ; for, 

 whilst they do not appear to become torpid until the temperature 

 sinks to 13 or 14 (Reaumur), they are even then readily roused, 

 and seem rather weak and morose than somnolent. 



