THE SENSE OF SMELL IN BIRDS 653 
In birds with relatively large olfactory lobes, such as Drom- 
aeus and Fulmarus, the sense of smell should of course be stronger 
than in the Corvidae. The writer knows, however, of no observ- 
ations upon the sense of smell in the first two birds other than 
the unsatisfactory ones already mentioned in this paper. 
Man is classed as a microsmatic animal, and the human olfac- 
tory organs are relatively very small; yet no one with a normal 
olfactory sense would deny that the human olfactory organs give 
their owners a large number of more or less intense impressions. 
It has not been practicable to make an exact comparison of the 
relative sizes of the organs of smell in birds and man, but those 
portions of the olfactory apparatus which are known in birds 
seem more extensive, relatively, in some birds, at least, than those 
of man. From a morphological standpoint, then, such birds 
as the Fulmar should be expected to have a more acute sense 
of smell than man possesses. 
It is quite possible that olfactory stimuli may simply rein- 
force reactions to other stimuli such as visual and tactile impres- 
sions. We may have mutual relations of stimuli such as were 
found by Yerkes (’05 and ’06), for the sense of hearing in the frog. 
Such birds as the duck or the flamingo, for example, may pos- 
sibly, in probing for food, have tactile sensations which are re- 
ceived through the huge trigeminus nerves, modified by olfactory 
stimuli. The negative results of most experiments with vultures 
may have been due to a mutual relation between the olfactory 
and visual senses which made it difficult for the bird to react to 
an olfactory stimulus only. 
The author agrees with Turner (’91), that the great reduction 
of the olfactory organs which has occurred in the higher birds 
would seem to indicate that the development of keen vision in 
birds is being accompanied by a degeneration of the olfactory 
sense which may result in its total loss, eventually. 
Though the doves in the experiments described on pp. 646-650, 
never learned to find their food with perfect accuracy during a 
series of studies which extended, twice a day, through the greater 
part of about nine months, it is evident that they were stimulated 
by at least one of the odorous materials used, 7.e., oil of bergamot. 
JOURNAL OF MORPHOLOGY, VOL. 22, NO. 3 
