Page:Popular Science Monthly Volume 6.djvu/160

148 smell displayed in its highest degree of power and perfection. Among ruminants, some pachyderms, and particularly among carnivorous mammals, the olfactory membrane attains the keenest sensitiveness. Buffon has described these animals with extreme exactness, in saying that they smell farther than they see, and that they possess in their scent an eye which sees objects not only where they are, but even wherever they have been. The peculiarity of scent in the dog is too well known to need more than an allusion.

If we can hardly give faith to those ancient historians who relate that vultures were attracted from Asia to the fields of Pharsalia by the smell of the corpses heaped together there after a famous battle, yet we must accept the assertions of naturalists so well qualified to observe as, for instance, Alexander von Humboldt. The latter relates that in Peru, and other countries of South America, when it is intended to take condors, a horse or cow is killed, and that in a short time the smell of the dead animal attracts a great number of these birds, though none had before that been seen in the country. Other more extraordinary facts are told by travelers. These must usually be received only with the greatest caution, because in most cases the sense of smell gains credit for what is due to the sense of sight, which, with these birds, is very keen and far-reaching. Yet, making allowance for exaggeration, it must be admitted that these animals have a very highly-developed sense of smell. Scarpa, who has made admirable researches on this subject, found that they refuse food which is saturated with odorous substances, and, as an odd instance, that a duck would not swallow perfumed bread till after it had washed it in a pond. The waders, which have the largest olfactory nerves, are also those birds that display the greatest keenness of scent. Reptiles have very large olfactory lobes, leading us to believe that they discern odors readily, but at present we know little of the impressions they are sensitive to in this respect. Fish also have an olfactory membrane. Fishermen have always remarked that they may be attracted or driven off by throwing certain odorous substances into the water. Sharks, and other voracious fish, collect in crowds and follow from very far about a body thrown into the sea. It is even said that, when blacks and whites are bathing together in latitudes where these fish abound, they particularly single out and pursue the more strongly odorous blacks. Nor are the crustacea indifferent to emanations which act on the olfactory nerve. The method used for attracting and taking crabs is familiar.

Regarding the lower animals we have only still more uncertain information, except as to insects. Entomologists maintain that scent is very delicate in most insects, and rely on plausible conjectures on this subject, but they do not as yet know what the seat of the sense of smell in insects is. When meat is exposed to the air, in a few moments flies make their appearance in a place where none had before