As is well known, the last vestiges of the taboo of the mother-in-law have not yet disappeared, though they survive only in humour, as do many other customs that were once seriously practised. In fact, there is no other form of relationship, whether by blood or by marriage, that is so subjected to the satire of daily life as well as to the witticisms and jokes of comic papers as is that of the unfortunate mother-in-law. Thus, the primitive taboo resting on the mother-in-law and also, even though in lesser degree, on the father-in-law, has registered itself in habits that are relatively well known. Graver results of the regulations of ancient custom are doubtless to be found in those prohibitions of union between relatives by marriage that still constitute essential elements of present-day laws. This, of course, does not mean that these prohibitions are unjustifiable or that they do not reflect natural feelings. They but exemplify the fact that every law presupposes a development which, as a rule, goes back to a distant past, and that the feelings which we to-day regard as natural and original had a definite origin and assumed their present character as the outcome of many changes. Alongside of these later forms of the taboo, and outlasting them, we have its most primitive form. This is the taboo which rests on the eating of certain foods, particularly the flesh of certain animals, though less frequently it applies also to occasional plants. The latter, however, probably represents a transference, just as does plant totemism. A particular example of such a taboo is the avoidance of the bean by the Grecian sect of Orphians and by the Pythagoreans whom they influenced. The taboo of certain animals survived much longer. But it was just in this case that there came an important shift of ideas which gave to the taboo a meaning almost the opposite of that which it originally possessed. Proof of such a change is offered by the Levitical Priests' Code of Israel. The refined casuistry of the priests prescribed even to details what the Israelite might eat and what was taboo for him. For the Israelite, however, this taboo was not associated with the sacred but with the unclean. The original taboo on the eating of the flesh of an animal related, in the totemic period, to the sacred animal. This is the taboo in its original form. The Australian shrinks from eating the flesh of his totem animal, not because it is unclean, but because he fears the revenge of demons if he consumes the protective animal of his group. In the Priests' Code, the sacred object has become entirely transmuted into an unclean object, supposed to contaminate all who eat of it. It is a striking fact, however, that the animals which are regarded as unclean are primarily the early totem animals--the screech-owl, the bat, the eagle, the owl, etc. Of the animals that live in or near the sea, only those may be eaten that have scales, that is, only fish proper, and not the snake-like fish.