ON THE INSTINCTS OF BIRDS. 123 
the mild temperature of the atmosphere in spring is 
suitable for hatching their eggs, and for producing a 
plentiful supply of that nourishment which is wanted 
for their young. This opinion he attempts to support 
by the fact that poultry, which have an abundance of 
food throughout the year, and are protected from the 
inclemency of the weather, lay their eggs at any 
season and never pair. But it should be recollected 
that this is not the case with Pigeons placed under 
‘similar circumstances, which do pair, though they 
produce only two young ones at a time; and that the 
Pheasant among our naturalized, and the Black Grouse 
among our native birds, though they have both large 
families to provide for, are, in their wild state, poly- 
gamous. Indeed it is evident from the anatomical 
and physiological researches of Mr. John Hunter and 
Dr. Jenner that the sexual connexions of birds, 
and the season at which they breed, depend upon 
certain conditions of their organization, and not upon 
any information derived from experience or instruction. 
The propensity to propagate their species in this 
class of animals is well known to be of periodical 
occurrence, and dissection clearly proves that it is 
always accompanied by a very perceptible alteration 
in the reproductive system. Besides, reclaimed birds, 
under the influence of a plentiful supply of nourishing 
food, shelter from the inclemency of the weather, and 
the various stimuli with which domestication is usually 
attended, may be kept in this state of sexual excita- 
