The usual modus operandi employed by Mexican herders, who cannot be surpassed in their vocation, to which they appear to take intuitively, although many of them serve an apprenticeship at it, which begins with early life and ends only by death, is, to send a youth who leads a goat in advance of the flock.  From some strange and unaccountable reason, the sheep will follow after him even to the crossing of rivers whose currents are deep and swift.  The shepherds, with their dogs to assist them when necessary, allow the herd to scatter over a space varying in its size, but always allowing sufficient area so that the animals can move on at their ease and at the same time be able to feed.  The danger above all others that is to be apprehended and guarded against, while thus travelling, is crowding; for, in this manner, when journeying through deep gorges in the mountains and over the precipitous banks of rivers, hundreds of sheep can be, and not unfrequently are, smothered.  When this crowding commences, it is next to impossible to arrest it; a sort of panic prevails over the entire herd, and they rush on, one on top of another, until a mass of dead and dying is thus piled up and a barrier is made; or else, until, as most frequently happens, a bridge of carcasses is formed over which the survivors pass in safety.  The Indians who inhabit the country on the various routes to California, have a strong predilection for mutton, which is a fact to bear in mind when migrating with this sort of property.  Such accidents as having a few sheep bitten by rattlesnakes, and also a certain percentage becoming foot-sore and breaking down from fatigue, are common to every herd that crosses the Rocky Mountains.  Economy in living is the great fundamental principle among the lower classes of the Mexicans; therefore, when a sheep is going to die from fatigue, or any simple disease, natural death is anticipated by the herders with the aid of the hunting-knife, and the meat, being dressed and cooked, is unhesitatingly eaten by them.  Next to the Mexican shepherd, his dog, although he is not generally a handsome animal, is found to be ever faithful in guarding the flocks.  The greatest enemy to the herds is the wolf; and in keeping them at bay, and preventing their inroads by night, the dog is capable of performing valuable service; hence, no band of sheep should cross the plains and mountains without a full complement of them.  It was at one of the frontier towns of California that Kit Carson disposed of his flock.  There having heard of the rapid and marvelous growth of San Francisco, he made up his mind to verify these reports with his own eyes, for he was well acquainted with its ancient aspect.