RANZANI ON SENSATION. 221 



intelligent author may be induced to follow up his investigations at 

 some future opportunity into more detail, as his resources are evidently 

 good as well as abundant. 



ON THE ORGANS OF SENSATION. 



BY PROFESSOR RANZANI, OF BOLOGNA*. 



As there are different kinds of sensations, the impressions which 

 arise from them will also be various. Such impressions, then, must 

 be made upon organs constructed in such a manner as to prove their 

 effects, and, consequently, to awaken in the mind corresponding sen- 

 sations. To these organs of which every animal possesses a certain 

 number the name of sensorium has been given. The organs of sense 

 are formed in different parts, and, with the exception of that of the 

 touch, are exceedingly limited. Among the parts which compose an 

 organ of sense, some serve to modify the impression, and others prove, 

 in an especial manner, its effect, and transmit it to the seat of the 

 mind. These ultimate parts of the sensorium, without which no reflex 

 sensations can be experienced, are called nerves. The nerves are 

 either visible or invisible ; those of the most minute animals will never 

 be evident to our eyes. When the nerves are perceptible, we recognise 

 them by means of those which are known, or we do not recognise them. 

 Poli, for example, in dissecting certain moluscous animals which 

 inhabit the Mediterranean sea, saw their nerves, described them, and 

 gave an exact figure of them ; yet did not consider them as nerves, 

 and therefore indicated them by a very different namef. Many nerves 

 of our own body are well known to us. Their figure, colour, and 

 structure, serve to guide us in judging of the nerves of other animals. 

 If the nerves of the latter bear no resemblance to ours, we shall not 

 regard them as nerves. Within these few years, the nerves of many 

 animals have been discovered, and, except in the minutest class, which 

 comprehends microscopic animals, they exist in every other animal 

 whose nerves have been observed and acknowledged. There can be 

 no doubt, then, that all animals have nerves, since all animals are 



* Translated from the Italian by James Flewker, Esq. of the Theatre of Anatomy, 

 Windmill-street. t Testacea utriusque Siciliae, &c. 



