OO _ 
THE ZooLocist—Aveust, 1876, _ 5021 
in turn. The adventitious birds increased by natural multiplication, till 
they outnumbered the true-born ones: what was engendered of necessity 
was perpetuated by unconscious volition, and finally became a fixed habit— 
the law of reproduction for the species. Much current reasoning on similar 
subjects is no better nor worse than this, and it all goes for what it is 
worth.” 
The Doctor also suggests that as the parasitic habits of the 
various species of Molothrus operate injuriously upon the in- 
crease of many birds, “the special check thus provided may be 
intended to preserve the delicate balance of some of Nature’s 
forces.” His remarks upon this subject are very interesting, as 
they naturally bear upon the economy of the cuckoo, concerning 
which there is much yet to be learned. We therefore do not 
hesitate to quote further from what he has to relate of the cow- 
bird :— 
“Tt does not appear that the cowbird ever attempts to take forcible 
possession of a nest. She watches her chance while the owners are away, 
slips in by stealth, and leaves the evidence of her unfriendly visit to be 
discovered on their return, in the shape of the ominous egg. The parents 
hold anxious consultation in this emergency, as their sorrowful cries and 
disturbed actions plainly indicate. If their nest was empty before, they 
generally desert it, and their courage in giving up a cosy home results in 
one cowbird the less. Sometimes, even after there is an egg of their own 
in the nest, they have nerve enough to let it go, rather than assume the 
hateful task of incubating the strange one. But if the female has already 
laid an egg or two, the pair generally settle into the reluctant conviction 
that there is no help for it; they quiet down after awhile, and things go on 
as if nothing had happened. Not always, however, will they desert even 
an empty nest; some birds have discovered a way out of the difficulty—it 
is the most ingenious device imaginable, and the more we think about it the 
more astonishing it seems. They build a two-story nest, leaving the ob- 
noxious egg in the basement. I want no better proof that birds possess a 
faculty indistinguishable, so far as it goes, from human reason; and such a 
case as this bears impressively upon the general question of the difference 
between reason and that faculty we designate by the vague and misleading 
term ‘instinct.’ The evidence has accumulated till it has become con- 
clusive, that the difference is one of degree, not of kind—that instinct is a 
lower order of reason—the arrest, in brutes, at a certain stage, of a faculty 
reaching higher development in man. Instinct, in the ill-considered, current 
sense of the term, could never lead a summer yellowbird up to building a 
two-story nest to let a cowbird’s eggs addle below. Such ‘instinct’ is 
SECOND SERIES—VOL. XI. 2P 
