CONCLUSION. 2T9 



ritl zones. It is thus that the instinct which carries 

 the foxes and white bears to the sea coast of our fro- 

 zen zone during winter, leads me to suppose that 

 the currents of the ocean bring them a supply of food, 

 which would not be the case, unless these currents 

 descended from an opposite pole. 



" There exists the greatest differences in respect 

 to the extent of the orbits of the different planets; one 

 requires only a month for its revolution round the 

 sun ; others, respectively, three months, eight months, 

 two years, twelve years, thirty years, and, finally, 

 nearly eighty-four years. To all these, a calculator 

 may find, or fancy that he finds, corresponding pe- 

 riods in the duration of vegetable and animal life, 

 He may compute that several kinds of insects, such 

 as butterflies, live between one month and eight; 

 others, such as the May bug, two years, or one year 

 of Mars Several birds and quadrupeds, among 

 others, goats are understood to live twelve years, or 

 a year of Jupiter; other quadrupeds thirty years, or 

 a year of Saturn; while the life of man may be oc- 

 casionally brought forward as completing the longest 

 period of all, the revolution of the Georgium Sidus. 

 A farthei- inquiry might lead such a speculator to 

 ascertain examples of still longer life in the animal 

 and vegetable world, and to find, perhaps, parallels 

 to the return of comets 



" Leaving these visionary speculations, I am to 

 observe, that the animals which die of old age go oft* 

 the stage as they came upon it, without being aware 

 of the change The last steps in the descent of life 



