(To THE EDITOR OF THE " SPECTATOR.") SIE,—The article in
the Spectator of May 20th upon the above subject opens up a wide field for investigation into the comparative anatomy of the nervous system, an aspect of scientific research which will probably throw much light upon the evolution of the senses in man and the higher vertebrates. The great adaptation to environment in Nature signifies an adjustment or fitness of special organs as a means to an end, and it is the study of this doctrine by naturalists that has served as one among other factors to explain away the mystery of special creations. In some mammals, as we know, the sense of smell is of the utmost importance, and is correspondingly developed,—it is the sense "to get and beget." Even in the lowest vertebrates, such as fishes— as anglers know who scent their bait with oil of aniseed, rhodium lignum, or other essential oils—what corresponds to the sense of smell is highly developed, and its cortical representation in the brain is correspondingly exten- sive. In mammals which have taken to an aquatic life (whales and dolphins) there is, on the other hand, no organ of smell, and consequently there can be no sense of smell, and there is certainly no representation of such organ in the brain. Your correspondent in the issue of May 27th is not quite accurate when he states that the mole, unlike the pig, does not use his nose for rooting in the ground, but forces his way on by means of his adaptive legs and feet, which scrape the soil to either side. If the mole is placed in a glass jar filled with earth, his tunnelling movement can be fully watched as he approaches the sides, and the special utility of the snout for digging can easily be demonstrated. Dr. G-. A. Watson has closely studied the habits of the mole and its " cousin " the shrew, and deductions from his exceedingly interesting histological researches into the comparative structure of the brain in these and other vertebrates are, I believe, shortly to appear in the "Archives of Neurology" for 1905.-1 am, Claybury.
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