UJEMORRIIAGIES. 209 



in the nose, there is, for the purpose of sense, a considerable 

 network of blood-vessels expanded on the external surface of 

 the nostrils, and covered only with thin and weak teguments. 

 From this circumstance it is, that upon any increased impetus 

 of the blood in the vessels of the head, those of the nose are 

 most easily broken ; and the effusion from the nose taking 

 place, it not only relieves the other extremities of the external 

 carotid, to which the arteries of the nose chiefly belong, but 

 relieves also, in a great measure, the system of the internal 

 carotid. For, from the internal carotid, certain branches are 

 sent to the nose, or spread out on its internal surface, and 

 probably inosculated with the extremities of the external carotid : 

 so that, whichsoever of the extremities are broken, the vis 

 derivationis of Haller will take place ; the effusion will relieve 

 the whole sanguiferous system of the head ; and the same 

 effusion will also commonly prevent an hsemorrhagy happening 

 at the same time in any other part of the body. 



DCCLVIII. From these principles, it will appear why 

 haemorrhagies of the nose, so frequent before the period of 

 puberty, or of the acme, seldom happen after these periods : 

 and I must observe further, that although they should occur, 

 they would not afford any objection to my doctrine, as such 

 haemorrhagies might be imputed to a peculiar laxity of the ves- 

 sels of the nose, and perhaps to a habit acquired with respect to 

 these vessels, while the balance of the system might be other- 

 wise duly adjusted. 



DCCLIX. When the process of the growth of the body goes 

 on regularly, and the balance of the system is properly adjusted 

 to the gradual growth of the whole, as well as to the successive 

 growth of the several parts, even a plethoric state does not pro- 

 duce any haemorrhagy, or at least any after that of the nose ; 

 but if, while the plethoric state continues, any inequality shall 

 also subsist in any of the parts of the system, congestions, hse- 

 morrhagic or inflammatory, may be still readily formed. 



DCCLX. In general, it may be observed, that, when the 

 several parts of the system of the aorta have attained their full 

 growth, and are duly balanced with one another, if then any 

 considerable degree of plethora remain or arise, the nicety of the 

 balance will be between the systems of the aorta and pulmonary 

 VOL. IT. o 



