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want others to do, their extraction of thorns and splinters from their own and others’ bodies, their modes of exhibiting affection, their natural hostility to strangers, and their gradual adoption of strangers into their group as they become better acquainted. For fuller information on these topics the reader may consult the works of Köhler and Yerkes, from which I have quoted.

I cannot, however, leave this topic without a few words on the family life of the apes and the care of parents for their offspring. Information on these topics is very meagre, because it is only very rarely that the larger apes have been bred in captivity. It has recently been established that the menstrual periods in female chimpanzees occur about every thirty days, and that the period of gestation is nine months—a fact ascertained from the birth of a young chimpanzee in the Abreu collection at Quinta Palatino, Cuba.

This baby chimpanzee was observed, soon after birth, in the lap of its mother, by whom it was cleaned and dried. It was quite devoid of hair except on the head. Lactation began on the second day, and the baby was nursed for several months. Incisor teeth appeared when the baby was two months old, and some of the molars developed during the next month. The mother was very solicitous for the welfare of her offspring. The father, who was somewhat morose, would often frighten the baby during his fits of temper, but was never known to molest it. Other male chimpanzees have been described as treating their young with gentleness and as playing with them.

The offspring of apes, as of most mammals, man included, receive more care and attention from the mother than from the father. Among the higher apes an adult male is often seen with one or a few adult females and a small group of younger individuals. The young cling tightly to the hair