I pass in silence the two large families which include the jerboa, the chinchilla, the biscacha, and the tushkan, or underground hare of South Russia, though all these small rodents might be taken as excellent illustrations of the pleasures derived by animals from social life.(15) Precisely, the pleasures; because it is extremely difficult to say what brings animals together--the needs of mutual protection, or simply the pleasure of feeling surrounded by their congeners. At any rate, our common hares, which do not gather in societies for life in common, and which are not even endowed with intense parental feelings, cannot live without coming together for play. Dietrich de Winckell, who is considered to be among the best acquainted with the habits of hares, describes them as passionate players, becoming so intoxicated by their play that a hare has been known to take an approaching fox for a playmate.(16) As to the rabbit, it lives in societies, and its family life is entirely built upon the image of the old patriarchal family; the young ones being kept in absolute obedience to the father and even the grandfather.(17) And here we have the example of two very closely-allied species which cannot bear each other--not because they live upon nearly the same food, as like cases are too often explained, but most probably because the passionate, eminently-individualist hare cannot make friends with that placid, quiet, and submissive creature, the rabbit. Their tempers are too widely different not to be an obstacle to friendship.