During the "running season," as it was called by the plainsmen, the whole nature of the herd was completely changed. Instead of being broken up into countless small groups and dispersed over a vast extent of territory, the herd came together in a dense and confused mass of many thousand individuals, so closely congregated as to actually blacken the face of the landscape. As if by a general and irresistible impulse, every straggler would be drawn to the common center, and for miles on every side of the great herd the country would be found entirely deserted. At this time the herd itself became a seething mass of activity and excitement. As usual under such conditions, the bulls were half the time chasing the cows, and fighting each other during the other half. These actual combats, which were always of short duration and over in a few seconds after the actual collision took place, were preceded by the usual threatening demonstrations, in which the bull lowers his head until his nose almost touches the ground, roars like a fog-horn until the earth seems to fairly tremble with the vibration, glares madly upon his adversary with half-white eyeballs, and with his forefeet paws up the dry earth and throws it upward in a great cloud of dust high above his back. At such times the mingled roaring--it can not truthfully be described as lowing or bellowing--of a number of huge bulls unite and form a great volume of sound like distant thunder, which has often been heard at a distance of from 1 to 3 miles. I have even been assured by old plainsmen that under favorable atmospheric conditions such sounds have been heard five miles. Notwithstanding the extreme frequency of combats between the bulls during this season, their results were nearly always harmless, thanks to the thickness of the hair and hide on the head and shoulders, and the strength of the neck. Under no conditions was there ever any such thing as the pairing off or mating of male and female buffaloes for any length of time. In the entire process of reproduction the bison's habits were similar to those of domestic cattle. For years the opinion was held by many, in some cases based on misinterpreted observations, that in the herd the identity of each family was partially preserved, and that each old bull maintained an individual harem and group of progeny of his own. The observations of Colonel Dodge completely disprove this very interesting theory; for at best it was only a picturesque fancy, ascribing to the bison a degree of intelligence which he never possessed. At the close of the breeding season the herd quickly settles down to its normal condition. The mass gradually resolves itself into the numerous bands or herdlets of from twenty to a hundred individuals, so characteristic of bison on their feeding grounds, and these gradually scatter in search of the best grass until the herd covers many square miles of country.