As birds have a full active life, with considerable variety of function, in usually complex environment, since, as we have already noticed, their sense-organs and nervous systems are highly developed, considerable exhibition of intelligence is to be expected. They seem to have great vividness of sense impressions, to judge from their power of recalling old haunts and old friends. Birds often return to the same place season after season, and they have been known to recognize an owner after the lapse of years. Their quickness of ear and power of retention are evidenced by the power some possess of learning to repeat sounds, both words and tunes. Some have exhibited marked fondness for music, and the æsthetic tastes of the bower-bird excite deserved admiration. Much more is known in regard to their marvelous hereditary, general, and largely automatic reasonable habits or “instincts” than in regard to their power of individually adapting their conduct to novel circumstances. Their beautiful and adroit contrivances of nest-building are very familiar instances of the former, but many instances of the latter have been recorded. As to feelings, it is hardly necessary to refer to their unexampled exhibition of sexual emotion in song and dance, parade, and display, or to the marvelous parental love and sacrifice expressed in their nest-building labors, in their prolonged incubation, and in their care for and courage in defending their brood. Subtler emotions of jealousy, both in connection with and altogether apart from sex, of affection for owners or associations, of sympathy for wounded or enfeebled fellows, are also not rarely exhibited. That a bird singing continuously for hours does not represent a rare height of emotion is not to be believed. It may be fairly said that the joyous song of the lark “at heaven’s gate” is an eloquent expression of emotion only surpassed perhaps by human music. MIMICRY --DAVID ROBERTSON In ordinary language a person who can imitate the accent, manner of talking, and acting of another is said to be a good mimic. In biology, however, the term mimicry is used in a metaphorical sense, being applied to the resemblance which one species of animal or plant frequently shows to another. This resemblance is usually of a protective character. It is evident that if the resemblance which a defenceless species of animal often has to a species well furnished with natural offensive and defensive weapons were a mere freak of nature, no satisfactory and philosophical explanation of the phenomenon could be given. Scientific investigators have to lay aside their wonder, and laboriously set about finding a solution to the most intricate and puzzling phenomena both in natural and physical science. Mimicry was first used by Mr. W. H. Bates to denote the advantageous and generally protective resemblance assumed by one species of animal or plant to another.