1890}. The Persistence of Plant and Animal Life. 529 
5. With a much hotter or colder earth; an earth where the 
weights of bodies were much greater or much less they are now; 
an earth not surrounded by an ocean of oxygen gas; or an earth 
deprived of the chemical force of our sun; some changes would 
be made in the modes in which life is perpetuated now, to suit 
these changed conditions of the planet, dut it is extremely unlikely 
that life would be extinguished by them, unless the conditions 
ehanged too suddenly. i 
6. The nature of these changes would be either: (a) to keep 
foreign matter flowing through the living body at about the rate 
it flows now, in which case the hydro-carbons would give place 
to some other group or groups of chemical elements to supply 
the framework of the plant or animals; or, (b) the rate of change 
of these groups of atoms being very much altered, the attributes 
of the living things of which they formed a part would be very 
much changed; or, (c) if both the elements themselves and the 
rapidity with which these resolved themselves into new combina- 
tions were changed, the diversity of the living things and of the 
world itself would be so different from what they are now that 
we have no means of forming the least conception of them. 
7. But in no one of these cases is it likely that 4f¢ would be- 
come extinct, though the present relations to each other of the - 
three kingdoms of nature would cease to be. 
