PARENTAL INSTINCT IN BIRDS. 247 
natural selection, a species must advance, or its extinction is 
simply a matter of time. 
The stimulus to advance, viz. increased competition, would 
be responded to by the fact that a sufficient number of young 
would present a sufficient supply of variations, so that natural 
Selection could grip the more favourable ones with sharper dis- 
crimination, and re-equip the species for its new environment. 
_ By reason of the female laying her eggs in a clutch and the 
male guarding them, the attention of both parents becomes 
localized on the nesting-site. A provd sense of ownership 
possesses the male, and a stealthy secretiveness the female. It 
does not require great imagination to see that the step from 
guarding the eggs to sitting on them is not a long one. The 
male to escape a superabundance of attacks would attempt to 
make himself less in evidence. When an enemy came in view 
he would bob down on the eggs, and, finding them warm and 
comfortable, would continue to sit. 
A curious fact is that among the birds, and even among the 
vertebrates generally, the male is generally the first to assume 
the responsibilities of domestic life. The male is the original 
mother. Consider the male’s psychic qualities—he is the most 
vigorous, most pugnacious of animals, and the sex that courts, 
and, indeed, shows himself to be the most impressionable of 
birds. The female is passive. 
_ Among the fishes, the male, almost without exception, is the 
only sex which shows any attachment to its eggs, and even then 
it is rather a piscine affection. It is the male Surinam Toad 
(Pipa americana) which carefully places the eggs on the back of 
the female. It is the male of Rhinoderma darwint, of Chili, who 
carries the female’s eggs; it is the male of the Obstetric Frog 
(Alytes obstetricans) who assumes maternal duties, and twists 
the eggs round his hind limbs. Even among the invertebrates 
the maternal male is not unknown, wiz. in the Pycnogonida. 
Among reptiles, however, it is apparently the female Python 
which sits on the eggs. Mammals, of course, produce sub- 
stantial anatomical evidence of the male’s former association 
with the female in suckling and in the care of the young. In the 
birds, of course, the males of each species in the Ratite incubate, 
while only in a few instances are the females allowed to have a 
