OF NATURAL HISTORY. 51^ 



With regard to the intentions of nature in changing forms, 

 a complete inveftigation of them exceeds the pov/ers of hu- 

 man refearch. One great intention, from the examples above 

 enumerated, Cannot efcape obfervation. In the animal world, 

 every fuccellive change is a new approach to the perfedlion of 

 the individuals. Men, and the larger animals, feme time af- 

 ter the age of puberty, remain ftationary, and continue to, 

 multiply their fpecies for periods proportioned to their ref- 

 peftive fpecies. When thofe periods terminate, they gradu- 

 ally decay till their final dilTolution. The fame obfervation 

 is applicable to the infect tribes, whofe transformations ftrike 

 us with wonder. The caterpillar repeatedly moults or cafts 

 off its fliin. The butterfly exifted originally in the body of 

 the caterpillar j but the organs of the fly were too foft, and 

 not fufficiently unfolded. It remains unfit to encounter the 

 open air, or to perform the functions of a perfedl: animal, till 

 fome time after its transformation into a chryfalis. It then 

 burfts through its envelope, arrives at a ftate of perfe(ftion, 

 multiplies its fpecies, and dies. All the changes in the vege- 

 table kingdom tend to the fame point. In the procefs of 

 growing, they are perpetually changing forms till they pro- 

 duce fruit, and then they decay. Some plants, like caterpil- 

 lars, go through all their transformations, death not excepted, 

 in one year. But others, like man and the larger animals, 

 befide the common changes produced by growth and the evo- 

 lution of different organs, continue for many years in a ilate 

 of perfedlion before the periods of decay and of diffolution 

 arrive. But thefe perennial plants undergo, every year, all 

 the viciflitudes of the annuals. They every year increafe 

 in magnitude, fend forth new leaves and branches, ripen and 

 dilTeminate their feeds, and, during winter, remain in a tor*, 

 pid ftate, or fuffer a temporary death. Thefe annual chang-. 

 es in trees, &c. have fome refemhlance to thofe of animalj 

 which produce at certain dated feafons only. 



