SCREAMING COW-BIRD 109 
presents itself to the mind as—to use the words of a 
naturalist of the eighteenth century, who was also a 
theologian and believed the Cuckoo had been created 
with such a habit—‘‘a monstrous outrage on the 
maternal affection, one of the first great dictates of 
nature.” An outrage, since each creature has been 
endowed with this all-powerful affection for the 
preservation of its own, and not another, species ; 
and here we see it, by a subtle process, an uncon- 
scious iniquity, turned from its purpose, perverted 
and made subservient to the very opposing agency 
against which it was intended as a safeguard! The 
formation of such an instinct seems indeed like an 
unforeseen contingency in the system of nature, a 
malady strengthened, if not induced, by the very 
laws established for the preservation of health, and 
which the vis medicatrix of nature is incapable of 
eliminating. Again, the egg of a parasitical species 
is generally so much larger, differing also in coloration 
from the eggs it is placed with, whilst there is such 
an unvarying dissimilarity between the young bird 
and its living or murdered foster-brothers that, un- 
reasoning as we know instinct, and especially the 
maternal instinct, to be, we are shocked at so glar- 
ing and flagrant an instance of its blind stupidity. 
In. the competition for place, the struggle for 
existence, said with reason to be most deadly between 
such species as are most nearly allied, the operations 
are imperceptible, and the changes are so gradual 
that the diminution and final disappearance of one 
species is never attributed to a corresponding in- 
