222 RANZANI ON SENSATION. 



capable of feeling ; nor, indeed, can there be sensations without such 

 organs. Therefore, greatly do all those err, who impugn this assertion 

 by declaring, that nerves do not exist in many animals, since they are 

 imperceptible to us. Our not seeing and not recognising the nerves, 

 unquestionably arises from the extreme minuteness of the animals, or 

 from the excessive subtlety of the nerves themselves, or from their want 

 of that resemblance to the nerves of our own body, which is required 

 to render them distinct and palpable. They who formerly employed 

 this argument would display gross ignorance to deny the existence of 

 nerves in those animals in which modern anatomists, through their 

 industry and diligence, have discovered them. But some one will 

 perhaps remark, should we not deny the faculty of feeling to plants, 

 because, as they have not been observed to possess nerves, we may 

 judge that they have not any ? I have already replied, that it is not 

 the want of nerves which leads men generally to suppose that plants 

 have no feeling ; it is, indeed, their not seeing, in the motions of 

 plants, any indications of sensation, which induces them to form such 

 opinions ; which thing being certain, the other proof, deduced from not 

 recognising nerves in them, acquires no little weight ; and which, in- 

 dependent of the former, would obtain no value. And in respect to 

 less perfect animals, the reflection that they so move, demonstrates to 

 us, that they have sensoria and sense, at least that of touch ; and they 

 perform numerous actions in a manner similar to that in which other 

 animals comport themselves, when they act voluntarily ; this, as I have 

 observed in another place, is the strongest motive for reputing them 

 animals, and therefore provided with nerves and all the other parts 

 which appertain to sensations and voluntary motions. And if in some 

 of them we are not able to discover nerves and muscles, we may easily 

 persuade ourselves that it arises from a quite different cause, and per- 

 haps from the total want of organs so constructed. 



The nerves, which we observe and acknowledge in different animals, 

 are soft whitish filaments, formed internally from medullary substance, 

 and invested with a membrane denominated the neurilema. Whether 

 these very subtle fibres are round or flattish-round whether they have 

 or have not an internal cavity whether they are internally pervaded 

 by a most active fluid, which deserves the name of nervous fluid or 

 whether they are destitute of such fluid, are researches which belong 

 to the physiologist and anatomist, and in respect of which we have 

 hitherto received no decisive evidence. In those animals in which the 



