268 LECTURE VI. 



dish," the air, and the moisture it contains. 

 Snails will live when covered up in a glazed 

 pan for more than a year. Now, though 

 I do not, under such circumstances, see 

 any thing astonishing in the instances of 

 reproduction which are reported to have 

 taken place, yet I should hesitate to admit 

 that the brain was ever perfectly repro- 

 duced, till such a fact was established by 

 observations on the future life of the ani- 

 mal, and by subsequent accurate anatomi- 

 cal examination. As far as I have observed, 

 divided earth-worms, and most decapitated 

 snails, perish ; and I know that w^e may 

 decollate the latter very completely, and yet 

 but partially remove the brain ; the repro- 

 duction of which would not then appear so 

 wonderful, for even in the higher classes of 

 animals, the life of parts seems to operate 

 so as to convert surrounding substances in- 

 to their own nature and structure. 



In the higher classes of animals, in 

 which distinct organs are allotted for carry- 

 ing on the vital functions, if parts be de^ 

 tached, they necessarily perish, for the 



