in his report to the Academy of Sciences. They refer to the fact of the hereditary transmission of habits originally impressed with care and art upon the ancestors. Of this fact I shall adduce other examples in the sequel; at present I only advert to M. Roulin's observations. The horses bred in the grazing farms on the table-land of the Cordillera, are carefully taught a peculiar pace, which is a sort of running amble. This is not their natural mode of progression, but they are inured to it very early, and the greatest pains are taken to prevent them from moving in any other gait. In this way the acquired habit becomes a second nature. It happens occasionally that such horses, becoming lame, are no longer fit for use; it is then customary to let them loose, if they happen to be well-grown stallions, into the pasture grounds. It is constantly observed that these horses become the sires of a race to which the ambling pace is natural, and requires no teaching. The fact is so well known, that such colts have received a particular name; they are termed 'aguilillas.' "The second fact is, the developement of a new instinct, which, as M. Roulin declares, seems to become hereditary in the breed of dogs found among the borderers on the river Madeleine, which are employed in hunting the pecari. I shall cite the author's own words:--'L'addresse du chien consiste à modérer son ardeur à ne s'attacher à aucun animal en particulier, mais à tenir toute la troupe en échec. Or, parmi ces chiens, on en volt maintenant qui, la première fois qu'on les amène au bois, savent dejà comment attaquer; un chien d'une autre espèce se lance tout d'abord, est environné, et quelle que soit sa force, il est dévoré dans un instant.'"