I think that the probability of the view I have taken is increased by another fact--namely, that the sudden display of scarlet colour sometimes affects timid animals with an extreme fear, just as, on the other hand, it excites those that are bold and aggressive to anger. Domestic sheep, forinstance, that vary greatly in disposition in different races or breeds, and even in different individuals, may be affected in the two opposite ways, some exhibiting extreme terror and others only anger at a sudden display of scarlet colour by the shepherd or herder. The persecution of a sick animal by its companions comes next under consideration. It will have been remarked, with surprise by some readers, no doubt, that I have set down as two different instincts this persecution of a sick or weakly individual by its fellows, and the sudden deadly rage that sometimes impels the herd to turn upon and destroy a wounded or distressed companion. It is usual for writers on the instincts of animals to speak of them as one: and I presume that they regard this sudden deadly rage of several individuals against a companion as merely an extreme form of the common persecuting instinct or impulse. They are not really one, but are as distinct in origin and character as it is possible for any two instincts to be. The violent and fatal impulse starts simultaneously into life and action, and is contagious, affecting all the members of the herd like a sudden madness. The other is neither violent nor contagious: the persecution is intermittent: it is often confined to one or to a very few members of the herd, and seldom joined in by the chief member, the leader or head to whom all the others give way. Concerning this head of the herd, or flock, or pack, it is necessary to say something more. Some gregarious animals, particularly birds, live together in the most perfect peace and amity; and here no leader is required, because in their long association together as a species in flocks, they have attained to a oneness of mind, so to speak, which causes them to move or rest, and to act at all times harmoniously together, as if controlled and guided by an extrane-ous force. I may mention that the kindly instinct in animals, which is almost universal between male and female in the vertebrates, is most apparent in these harmoniously acting birds. Thus, in La Plata, I have remarked, in more than one species, that a lame or sick individual, unable to keop pace with the flock and find its food, has not only been waited for, but in some cases some of the flock have constantly attended it, keeping close to it both when flying and on the ground; and, I have no doubt, feeding it just as they would have fed their young.