PEE, AQOLOGLS T 

No. 805.—July, 1908. 

SPECULATIONS ON THE ORIGIN AND DEVELOPMENT 
OF THE PARENTAL INSTINCT IN BIRDS. 
By Bruce F. Cummines. 
i 
Brrps do not show a great many gradational types from 
simple to complex forms in the development of this instinct, but 
there are sufficient to indicate the base-lines along which it has 
progressed. Allowing alwaysa broad margin for various circum- 
stances which, wholly unknown to us, may have considerably 
modified its development or altered its course, I hope to suggest 
in the following paper the necessary conditions for its origin, 
and the forces which have moulded its subsequent advance- 
ment. 
I assume that the instinct, at its earliest dawn, originated 
primarily in an unconscious way by the natural selection of 
chance favourable variations of unconscious habit, for it seems 
evident that a bird would find no just cause for any self-sacri- 
ficing attention to a hard uncomfortable object of which it has 
just ridded itself, and which we call an egg. And so Romanes 
has pointed out that the incubation instinct can only be explained 
as arising from the results of natural selection, and not as an 
action, originally intelligent, since stereotyped into mechanical 
instinct, as the reason why they sit could never have presented 
itself to the birds, for it would imply at least a scientific know- 
ledge of the properties of the germinal area of the egg. 
Zool. 4th ser. vol, XITI., July, 1908. : U 
