33 VIGNETTES FROM INVISIBLE LIFE. 



supposed. Underneath the appearances is seen the 

 one continuous stream of life, modified by its en- 

 vironment, and branching off in various courses, 

 more or less complex according to the obstacles to 

 be overcome, but always preserving its own essen- 

 tial character. This being so, while similarities 

 must appear in the several branches, one is not sur- 

 prised at not finding any sharp dividing lines, and 

 is not disposed to wrangle over classifications which 

 do not exist in nature. The substance or the 

 matter of life is found to be plastic, and hence 

 variable ; intelligent, and therefore adapting itself 

 to its environment ; is progressive ever aiming at 

 the highest possibilities of existence. All its many 

 phases are seen to be the natural outcome of these 

 its main characteristics, from the simple bit of plastic 

 matter we name the Amoeba, up to man himself. 



To come to the main object of this paper. The 

 almost invisible forms of life are operated on by 

 the same causes as the larger and more complex 

 organisms ; and the reason why a Melicertan builds 

 a house is the same as that which develops a thorny 

 covering for the hedgehog. Self-preservation is tl.e 

 first object to be secured ; and the varying devices 



