VOYAGE FROM NEW YORK TO RIO DE JANEIRO. 43 
number of layers, all of which contain the remains of dis- 
tinct populations. These different sets of inhabitants who 
have possessed the earth at successive periods have each 
a character of their own. The transmutation theory in- 
sists that they owe their origin to gradual transformations, 
and are not, therefore, the result of distinct creative acts. 
All agree, however, that we arrive at a lower stratum where 
no trace of life is to be found. Place it where w r e will: 
suppose that we are mistaken in thinking that we have 
reached the beginning of life with the lowest Cambrian 
deposit ; suppose that the first animals preceded this epoch, 
and that there was an earlier epoch, to be called the Lauren- 
tian system, beside many others older still ; it is nevertheless 
true that geology brings us down to a level at which the char- 
acter of the earth's crust made organic life impossible. At 
this point, wherever we place it, the origin of animals by de- 
velopment was impossible, because they had no ancestors. 
This is the true starting-point, and until we have some facts 
to prove that the power, whatever it was, which originated 
the first animals has ceased to act, I see no reason for refer- 
ring the origin of life to any other cause. I grant that we 
have no such evidence of an active creative power as Science 
requires for positive demonstration of her laws, and that 
we cannot explain the processes which lie at the origin of 
life. But if the facts are insufficient on our side, they are 
absolutely wanting on the other. We cannot certainly con- 
sider the development theory proved, because a few natu- 
ralists think it plausible : it seems plausible only to the 
few, and it is demonstrated by none. I bring this subject 
before you now, not to urge upon you this or that theory, 
strong as my own convictions are. I wish only to warn 
you, not against the development theory itself, but against 
