which would foil the eye; but it would be also impossible, because the complications of movement would confuse it. But, where the optical sense fails, the auditory sense succeeds. The membrane of the ear receives the torrent of motion, and transmits it with all its harmonies. In an orchestra, where scores of instruments are playing through the whole compass of the scale, the air is cut into waves by every complexity of vibration—grave tones mingle with shrill, soft with harsh, fundamentals are merged in overtones, and the storm of impulses is shot with the speed of rifle-bullets against the tympanum; and yet there is no confusion. In all their infinite diversity of qualities the waves are legible to the little membrane. It vibrates to the lowest and to the highest, to each and all, and telegraphs the whole performance with incomprehensible exactness to its cerebral destination and an exquisite work of art is produced in the sphere of pleasurable feeling and critical intelligence.
Our glance at this fascinating subject has been very imperfect, but, if any care to pursue it, we recommend them to the admirable book of Prof. Tyndall, "On Sound," to which we are indebted for the foregoing illustrations, and for many of the facts stated.
WHAT is instinct? In what does it differ from intelligence? What explanation can be given of it in the present state of the sciences of life? All these are questions to which a positive answer is asked for the first time in our day. Philosophers and moralists do not in our time concern themselves with the relations or the differences between instinct and intelligence; for they have no means of solving problems that particularly concern biology. Without going farther back, we remember Descartes's strange notion of animal machines, adopted by Bossuet, and the whole seventeenth century; but at this time biologists in their turn attack the problem; anatomy and physiology will perhaps give us the solution sought in vain at the hands of philosophic and religious systems since the days of Aristotle and St. Thomas.
George Cuvier was the first to draw a clear distinction between instinct and intelligence, in the second edition of the "Animal Kingdom" (1829), in which he digests the works published during the course of several years, by his brother Frédéric. The latter, placed in control of the menagerie of the museum, believed that it pertained