38 COSMIC PHILOSOPEY. [pt. ii. 



defined species which propagate themselves through long 

 ages with relative stability of character, the number of inter- 

 mediate individuals which ever come into existence must be 

 relatively small. We have next to note that, even of this 

 relatively small number of individuals, a still smaller rela« 

 tive number are likely to leave after death a permanent fossil 

 record of their existence. 



In the first place it is only by a rare combination of cir- 

 cumstances that any plant or animal gets fossilized at all. 

 The chances were nearly infinite against the preservation of 

 any of the very earliest organisms, with their soft and speedily 

 decaying textures. The higher land animals, on the other 

 hand, owe their occasional preservation to the accidents of 

 dying in sheltered caves, or of being covered with blown 

 sand or peat-moss, or of being frozen in Arctic ice. Trees 

 with solid trunks, littoral and marine animals, especially 

 crustaceans and shell-covered moUusks, are more likely to be 

 preserved than other organisms. But, in the second place, 

 the majority of the organisms once fossilized are afterwards 

 destroyed along with the sedimentary strata which contain 

 them. Since there have been several enormously long alter- 

 nating periods of elevation and of subsidence, it follows that 

 all the older sedimentary strata must have been metamor- 

 phosed by volcanic heat. These oldest rocks have sunk to a 

 depth of six or eight miles, down below the ocean-floor, 

 where they have been metamorphosed by the heat of the 

 molten liquid below, and whence they have again been slowly 

 shoved up above water-level, with all traces of their organic 

 contents obliterated. This process must have occurred so 

 many times as to have destroyed all but the later records of 

 life. The title "palaeozoic," formerly applied to. the Silurian 

 rocks, is a misnomer. It was formerly supposed that there 

 were no fossil-bearing rocks below the Silurian. But within 

 a few years the Cambrian and Laurentian strata have been 

 discovered, carrying us back into an antiquity nearly twice aa 



