250 THE ZOOLOGIST. 
will not suggest that the Plover is fully conscious of the signi- 
ficance of her ‘‘lame assumptions,”’ but in a case like this, if 
we lamely assume the habit to be a blind instinct, we are only 
raising a dust and then complaining that we cannot see. When 
Spencer calls instinct ‘‘ compound reflex action” nobody is any 
the wiser, but if we accept that every instinct is mingled with 
‘a, little dose of reason,’ as Huber said, then the clouds lift. 
We understand, then, the relations between instinct and reason ; 
reason and intelligence increase at the expense of instinct, just 
as inhibition gains control over reflex action, and in proportion 
with the growth of independent volition. 
Nothing is more certain that when birds possessed no parental 
instinct the young hatched in an active condition, so that they 
were able to look after themselves; but when parental instinct 
had advanced sufficiently the young came to be born in a naked 
and helpless condition, for the male, having permanently ac- 
quired the habit of guarding the eggs, would next begin to guard 
the young birds that hatched from those eggs. And the result 
of this was that there occurred the possibility of the young 
hatching in a less developed state, and in a more or less helpiess 
condition. 
But the benefits that would accrue from this are not at first 
sight particularly obvious. Of course, when birds come to sit, 
smaller eggs would be a necessity, or otherwise the parents 
would be unable to cover the whole clutch; while extremely 
large eggs would take a long time to hatch and cause exhaustion 
to the sitting bird. Again, the reduction of the food-yelk would 
benefit the producer—the hen—and the young would become 
healthier. 
Among those species where the helpless nestling chiefly 
obtains, it will be found that they are for the most part arboreal 
in their habits and great fliers. They are not runners or swim- 
mers. Consequently the young do not possess any running or 
swimming ability, and the parents build their nests for the most 
part in trees. If their young, therefore, developed the temporary 
art of ambulation before the acquisition of the permanent power 
of flight, they would soon run over the edge of the nest and break 
their necks. If, on the contrary, they were hatched already with 
the power of flight, as is the case with the Megapode of Celebes; 
