They appear, however, to have no appreciation of mimetic and warning colours, and have therefore not influenced in any way the evolution of mimetic resemblances dependent upon hues and patterns.
It is advantageous therefore that the numbers of the mimetic species should be fewer than those of the model; and this appears to be achieved in some cases by the individuals of the mimetic species dividing themselves between two or more models.
Between spiders and ants or spiders and beetles; yet even in this case both mimic and model have in common certain fundamental structural points to which the finishing touches completing the mimetic likeness are superadded.
Nevertheless, as explained below, it seems to be highly probable that ant-imitating insects and spiders, when the resemblance is dependent to a greater extent upon size, shape and movement than upon tint, have acquired their mimetic likeness especially to protect them from the attacks of such insect-enemies as predaceous wasps of the family Pompilidae, flies of the family Asilidae, and from socalled parasitic hymenoptera of the family Ichneumonidae, as well as from other insect-eating Arthropods.
The sub-species polytrophus from the Kikuyu Escarpments also has the planemoides and cenea forms and another form trimeni, which is intermediate between the unmodified female of antinorii and hippocoon, and like the latter is mimetic of Amauris niavius dominicanus.
Very commonly different species of aculeate Hymenoptera, inhabiting the same district, form the centres of mimetic attraction for insects of various orders, so that a considerable percentage of the insect-fauna can be arranged in groups according to the pattern of the particular model the species have copied.
MIMICRY, in zoology, the deceptive and advantageous resemblance presented by defenceless and edible species of animals to other species of animals living in the same locality, which are harmful or distasteful and are consequently avoided by all or by a majority of the enemies of the class to which the mimetic and usually the mimicked species belong.
But in no case does it appear that the modifications in shape and colour, which contribute to bring about a mimetic resemblance, are greater and more elaborate than those which result in the simpler examples of ordinary protective resemblance.
As Frazer notes (Golden Bough, 2 227), this festival appears to belong to the large class of mimetic charms designed to quicken the growth of vegetation; the marriage of Zeus and Hera would in this case represent the union of the king and queen of May.
While polysymmetry is solely conditioned by the manner in which the mimetic twin is built up from the single crystals, there being no change in the scalar properties, and the vector properties being calculable from the nature of the twinning, in the case of polymorphism entirely different structures present themselves, both scalar and vector properties being altered; and, in the present state of our knowledge, it is impossible to foretell the characters of a polymorphous modification.