PLANARIA GRAMINEA. 125 



rished on the twenty-eighth of October, 

 and the larger on the thirtieth, without any 

 sensible cause for the death of either. 



We know that there are certain animals 

 whose life draws to a conclusion on the at- 

 tainment of maturity ; and there are some 

 which die in giving birth to their young. 

 Many, among the insect tribes, which have 

 passed a protracted interval in successive 

 stages, have but a transient enjoyment of 

 existence in the perfect state. The butter- 

 fly, whose gaudy colours announce the ap- 

 proach of summer, seldom witnesses its 

 termination. When the immutable laws 

 for the conservation of the species are ful- 

 filled, the males of the honey-bee are des- 

 tined to perish by violence, at an appoint- 

 ed season ; and the ephemera of the morn- 

 ing scarce survives the close of day. Nay 

 more; the volvox globator, a beautiful green 

 spherical animal, includes several successive 

 generations at once within its body. All 

 the vital functions are performed ; it origi- 

 nates, grows, and reaches perfection. Then 



