I have observed that the helpless young of some of the mammals I have just mentioned seem at first to have no instinctive understanding of the language of alarm and fear in the parent, as all young-birds have, even before their eyes are open. Nor is it necessary that they should have such an instinct, since, in most cases, they are well concealed in kennels or other safe places; but when, through some accident, they are exposed, the want of such an instinct makes the task of protecting them doubly hard for the parent. I once surprised a weasel (Galictis barbara) in the act of removing her young, or conducting them, rather; and when she was forced to quit them, although still keeping close by, and uttering the most piercing cries of anger and solicitude, the young continued piteously crying out in their shrill voices and moving about in circles, without making the slightest attempt to escape, or to conceal themselves, as young birds do. Some field mice breed on the surface of the ground in ill-constructed nests, and their young are certainly the most helpless things in nature. It is possible that where this dangerous habit exists, the parent has some admirable complex instincts to safeguard her young, in addition to the ordinary instincts of most animals of this kind. This idea was suggested to me by the action of a female mouse which I witnessed by chance. While walking in a field of stubble one day in autumn, near Buenos Ayres, I suddenly heard, issuing from near my feet, a chorus of shrill squealing voices--the familiar excessively sharp little needles of sound emitted by young, blind and naked mice, when they are disturbed or in pain. Looking down, I saw close to my foot a nest of them--there were nine in all, wriggling about and squealing; for the parent, frightened at my step, had just sprung from them, overturning in her hurry to escape the slight loosely-felted dome of fine grass and thistledown which had covered them. I saw her running away, but after going six or seven yards she stopped, and, turning partly round so as to watch me, waited in fear and trembling. I remained perfectly motionless--a sure way to allay fear and suspicion in any wild creature,--and in a few moments she returned, but with the utmost caution, frequently pausing to start and tremble, and masking her approach with corn stumps and little inequalities in the surface of the ground, until, reaching the nest, she took one of the young in her mouth, and ran rapidly away to a distance of eight or nine yards and concealed it in a tuft of dry grass.