540 SMELL. 



" It appears the principal, not to say the sole, use of the si- 

 nuses* 1 , to supply this watery fluid, which is perhaps first con- 

 veyed to the three meatus of the nostrils and afterwards to the 

 neighbouring parts of the organ of smell, preserving them in that 

 constant state of moisture which is indispensable to the perfection 

 of smell. 



" The sinuses are so placed, that, in every position of the head, 

 moisture can pass from one or other of them into the organ of 

 smell. 



" The principal seat of smell, the fungous portion of the 

 nasal membrane, besides numerous blood-vessels, remarkable for 

 being more liable to spontaneous hemorrhage than any others in 

 the body, is supplied by nerves, chiefly the first pair *, which are 

 distributed on both sides of the septum narium, and also by two 

 branches of the fifth pair. The former appear to be the seat of 

 smell f : the latter to serve for the common feeling of the part, 

 that excites sneezing, &c." 



The olfactory nerves arise from the pulpy substance at the 

 anterior part of the internal convolutions of the middle lobes, of 

 course at the base of the cerebrum. The filaments are surrounded 

 along way with pulpy substance, approach each other, and usually 

 form three roots, which also unite, and where they unite a trian- 

 gular enlargement is produced : but the nerve soon contracts 

 and runs in a triangular groove at the inferior surface of the an- 

 terior lobe on the upper surface jof the sphenoid bone. The 

 two nerves converge as they approach the ethmoid, and at last 

 form an oval bulbous expansion, containing a great deal of grey 

 pulpy substance on the cribriform plates. From this soft bulb 



d " In my Prolus. de Sinibus Frontal., Getting. 1779. 4to,, I have brought 

 forward many arguments from osteogeny, comparative anatomy, and pathological 

 phenomena, to prove that these sinuses contribute indeed to the smell, but little 

 or nothing to voice and speech, as was believed by many physiologists." 



e " Metzger, Nervorum Primi Paris Historia. Argent. 1 766. 4to. reprinted 

 in Sandifort's Thesaurus, vol. iii. 



Scarpa, Anatomic, Annotat. 1. ii. tab. i. iiV 



f " This is shown by pathological dissection and comparative anatomy. Thus 

 in Loder's Observ. Tumoris Scirrhosi in Sasi Cranii reperti, Jen. 1779. 4to. is a 

 case of anosmia, following a compression of the first pair by a scirrhus. We 

 learn, from comparative anatomy, that in the most sagacious mammalia, v. c. 

 elephants, bears, dogs, bisulcous ruminants, hedgehogs, &c., the horizontal plate 

 of the cribriform bone is very large, and perforated by an infinity of small canals, 

 each of which contains a filament of the olfactory nerve." 



