SECT. XXXIX. $. GENERATION, 579 



bles ; then that part of the retina, which gives us 

 the perception of fnow, muft at that time be white ; 

 and that which gives us the perception of grafs, 

 mull be green. 



Then if by the laws of imitation, as explained 

 in Section XIL 33. and XXXIX. 6. the extremities 

 of the nerves of touch in the rete muKZofum be in- 

 duced intofimilar action, the fkin or feathers, or 

 hair, may in like manner fo difpofc their extreme 

 fibres, as to reflect white ; for it is evident, that all 

 thefe parts were originally obedient to irritative mo- 

 tions during their growth, and probably continue 

 to be fo ; that thofe irritative motions are not liable 

 in a healthy ftate to be fucceedcd by fenfation ; 

 which however is no uncommon thing in their dif- 

 eafed ftate, or in their infant ftate, as in plica po- 

 lonica, and in very young pen-feathers, which are 

 ftill full of blood. 



It was fhewn in Section XV. on the Production of 

 Ideas, that the moving organ of fenfe in fome cir- 

 cumflances refembled the object which produced 

 that motion. Hence it may be conceived, that the 

 rete mucofum, which is the extremity of the nerves 

 of touch, may by imitating the motions of there- 

 tina become coloured. And thus, like the fable 

 of the camelion, all animals may poflefs a tendency 

 to be coloured fomewhat like the colours they moil 

 frequently infpect ; and finally, that colours may 

 be thus given to the egg-fhell by the imagination of 

 the female parent ; which fhell is previoufly a mu- 

 ous membrane, indued with irritability, without 

 which it could not circulate its fluids, and incre^fe 

 in its bulk. Nor is this more wonderful than that 

 a fingle idea of imagination fliould in an inftant co- 

 lour the whole furface of the body of a bright fear- 

 let, as in the blufh of fhame, though by a very* 

 different procefs. In this intricate fubject nothing 

 loofe analogical conjectures can be had, which 



roay 



