The tribes of Central Australia, especially the Arunta, the Loritja, the Kaitish, the Unmatjera, and the Ilpirra,[312] make constant use of certain instruments in their rites which are called the _churinga_ by the Arunta, according to Spencer and Gillen, or the _tjurunga_, according to Strehlow.[313] They are pieces of wood or bits of polished stone, of a great variety of forms, but generally oval or oblong.[314] Each totemic group has a more or less important collection of these. _Upon each of these is engraved a design representing the totem of this same group._[315] A certain number of the churinga have a hole at one end, through which goes a thread made of human hair or that of an opossum. Those which are made of wood and are pierced in this way serve for exactly the same purposes as those instruments of the cult to which English ethnographers have given the name of "bull-roarers." By means of the thread by which they are suspended, they are whirled rapidly in the air in such a way as to produce a sort of humming identical with that made by the toys of this name still used by our children; this deafening noise has a ritual significance and accompanies all ceremonies of any importance. These sorts of churinga are real bull-roarers. But there are others which are not made of wood and are not pierced; consequently they cannot be employed in this way. Nevertheless, they inspire the same religious sentiments. In fact, every churinga, for whatever purpose it may be employed, is counted among the eminently sacred things; there are none which surpass it in religious dignity. This is indicated even by the word which is used to designate them. It is not only a substantive but also an adjective meaning sacred. Also, among the several names which each Arunta has, there is one so sacred that it must not be revealed to a stranger; it is pronounced but rarely, and then in a low voice and a sort of mysterious murmur. Now this name is called the _aritna churinga_ (aritna means name).[316] In general, the word churinga is used to designate all ritual acts; for example, _ilia churinga_ signifies the cult of the emu.[317] Churinga, when used substantively, therefore designates the thing whose essential characteristic is sacredness. Profane persons, that is to say, women and young men not yet initiated into the religious life, may not touch or even see the churinga; they are only allowed to look at it from a distance, and even this is only on rare occasions.[318]