ABSTRACT
Familiarity with animals, such as the bird or the dog, calls to mind different roles for olfaction. The dog, is an animal in which olfaction is thought to play a major role. In the literature regarding animal olfaction, the terms "microsmatic" and "macrosmatic" are often used. The evolution of olfaction must be deduced mainly through study of living forms. A more intimate relation between gustation and olfaction during the act of feeding was established and the physiological integration of all the associated sensory information led to the appearance of a primitive amygdala. Olfaction particularly has been implicated in homing behavior of salmon by observations of the effects of sectioning the olfactory nerves. Olfaction seems to have been a prominent feature of the sensory equipment of the earliest vertebrates. The origin of the vertebrate olfactory receptor may therefore have been from any of the invertebrate Metazoa.
