128 VIGNETTES FROM INVISIBLE LIFE. 



cessant application ; and would probably result in 

 other beneficial modifications of structure to har- 

 monise with it. 



It should be further observed, that in the still 

 water habited by the Conochilus, there is no danger 

 attending this motion corresponding to that which 

 would be the case in open running streams, where 

 such delicate bodies would every now and then be 

 in danger of transportation by floods beyond the 

 sources of their regular food supply. Hence the 

 attachment to water-plants, in the case of Meyalo- 

 trocha, Lacinularia, and other allied organisms, and 

 the power temporarily to do so by other more active 

 and powerful creatures. The banks of the ponds 

 (under the water-worn and projecting edges of 

 which Conochilus is generally found) afford suffi- 

 cient refuge, when the rising waters threaten them 

 with danger in this direction. 



It is thus that Nature ever works ; adapt- 

 ing herself to ever- changing conditions, and 

 evolving new forms and varieties of life and 

 motion. 



In the almost infinite variety of forms which 

 life assumes on this earth there are but two great 



