1877. ] Catastrophism and Evolution. 469 
life. These effects would, I conceive be, first, extermination ; 
secondly, destruction of the biological equilibrium, thus violating 
natural selection; and thirdly, rapid morphological change on 
the part of plastic species. When catastrophic change burst in- 
upon the ages of uniformity, and sounded in the ear of every liv- 
ing thing the words “ change or die,” plasticity became the sole 
principle of salvation.’ Plasticity, then, is that quality which, 
in suddenly enforced physical change, is the key to survival and 
prosperity. And the survival of the plastic, that is of the rapidly 
and healthily modifiable during periods when terrestrial revolu- 
tion offers to species the rigorous dilemma of prodigious change 
or certain death, is a widely different principle from the survival 
of the fittest in a general biological battle during terrestrial uni- 
formity. In one case it is an accommodation between the indi- 
vidual organism and inorganic environment, in which the most 
yielding and plastic lives. In the other it is a Malthusian death 
struggle, in which only the victor survives. At the end of a 
period of uniformitarian conditions, the Malthusian conqueror, 
being the fittest, would have won the prize of survival and as- 
cendency. Suppose now an interval of accelerated change. At 
the end only the most plastic would have deviated from their late 
forms and reached the point of successful adaptation, which is 
survival in health. Whatever change takes place by natural 
selection in uniformitarian ages, according to Darwin, advances 
by spontaneous, aimless sporting and the survival of those varie- 
ties best adapted to surrounding conditions, and of these condi- 
_ tions the biological relations are by far the most important of all. 
y that means, and by that alone, it is asserted, species came 
into existence, and inferentially all the other forms from first to 
last. This is the gospel of chance. 
If the out-door facts of American geology shall be admitted to 
r me out in my assertion of catastrophes, and if the epochs of 
maximum vital change do, as I hold, coincide with the epochs of 
catastrophes, then that coincidence should be directly determina- 
ble in the field. I confidently assert that no American geologist 
will be able to disprove the law that in the past every one of the 
great breaks in the column of life coincide with datum points of 
catastrophe. It remains to be determined how far this coinci- 
dence is the expression of environmental cause, responded to in 
terms of vital effect. | 
From a comparison of the list and character of geological 
Changes in America with those mysterious lines across which no 
