SECT. XIV. 3. PRODUCTION OF IDEAS. 133 



tiilation like thofc of the female ; but which feem 

 now to be of no further ufe, owing perhaps to 

 f'ome change which thefe animals have undergone 

 in the gradual pro^refiicn of the formation of the 

 earth, and of all that it inhabit. 



Thefe feven laft mentioned fenfes may properly 

 be termed appetites, as they differ from thofe of 

 touch, light, hearing, tafte, and fmell, in this ref- 

 pecl ; that they are affected with pain as well by the 

 defect of their objects as by the excefs of them, 

 which is not fo in the latter. Thus cold and hunger 

 give us pain, as well as an excefs of heat or fatiety; 

 but it is not fo with darknefs and file nee. 



IX. Before we conclude this Sedion on the or- 

 gans of fenfe, we muft obferve, that, as far as we 

 know, there are many more fenfes, than have been 

 here mentioned, as every gland feems to be influ- 

 enced to feparate from the blood, or toabforb from 

 the cavities of the body, or from the atmofphere, 

 its appropriated fluid, by the fHmulus of that fluid 

 on the living gland ; and not by mechanical capil- 

 lary abforption, nor by chemical affinity. Hence it 

 appears, that each of thefe glands mull: have a pe- 

 culiar organ to perceive thefe irritations, but as 

 thefe irritations are not fucceeded byfenfation, they 

 have not acquired the names of fenfes. 



However when thefe glands are excited into mo- 

 tions ftronger than ufual, either by the acrimony 

 of their fluids, or by their own irritability being 

 much increafed, then the fenfation of pain is pro- 

 duced in them as in all the other fenfes of the body ; 

 and thefe pains are all of different kinds, and hence 

 the glands at this time really become each a different 

 organ of fenfe, though thefe different kinds of pain 

 have acquired no names. 



Thus a great excefs of light does not give the 

 idea of light but of pain ; as in forcibly opening 

 the eye when it is much inflamed. The great ex- 

 qefs of preffure or diftention, as when the point of 



a pin 



