Abstraction also enters, to a certain extent, into the religious beliefs of most of these negroes, in whom primal materialism has given place to the unbridled superstition of crude spiritism. The curious habit these people have of scraping a little bone dust from the skull of a dead ancestor and then eating it with their food, thus, as they think, transmitting from the dead to the living the qualities of the former, is close kin to, and, in my opinion, is probably derived from, a worship of the generative principle. When we take into consideration the fact that circumcision, _extensio clitoridis_, and other phallic rites are exceedingly common and prevalent among these negroes, this opinion has strong evidence in its support.[12] [12] Negroes of Benin and Sierra Leone (Bosman, _loc. cit._, p. 526), Mandingoes (Waitz, vol. ii, p. 3), Bechuanas (Holub, _loc. cit._, p. 398); quoted also by Westermarck, _Human Marriage_, p. 206. The Wa-kamba may have some idea of immortality, though observers have never been able to determine this definitely. "The dead bodies of chiefs are not thrown to the hyenas, as with the Masai, but are carefully buried instead.... The bodies of less important members of the tribe are simply thrown to the hyenas."[13] [13] Gregory: _The Great Rift Valley_, p. 351. In this people, religious ideas are exceedingly primitive and indefinite. They seem to propitiate nature, however, when they wish rain, for they offer up to the rain-spirit votive offerings of bananas, grain, and beer, which they place beneath the trees. This seems to be their only religious rite according to Gregory, who, in all probability is in error. For, in the next sentence, he informs us that these negroes practice circumcision. He thinks that they perform this operation for sanitary reasons, "as the natives have continually to ford streams and wade through swamps abounding in the larvæ of _Bilharzia haematuria_, the rite no doubt lessens the danger of incurring hæmaturia."[14] This is bestowing upon ignorant and savage negroes a psychical acuteness which far transcends that of the laity of civilized races! What do the Wa-kamba know of sanitation, hæmaturia, and the larva of Bilharzia![E] Circumcision among these people always occurs at puberty, and is, unquestionably, a phallic rite. Parenthetically, it may be stated here that a few of the primitive peoples still in existence appear to have grasped the idea of the life-giving principle, and to have established worship of the _functio generationis_ without having experienced certain preliminary psychical stages necessary for its evolution from nature-worship. I believe, however, that this is apparent and not real; nature-worship, very probably, at one time existed among all these people. [14] Gregory: _The Great Rift Valley_, p. 351.