The significance of primitive ornament has also been studied in another way. In a number of cases it has been shown that series can be arranged in which we may place at one end a realistic representation of an object. By degrees we may pass to more and more conventional forms that show each a distinct similarity to the preceding one, but end in a purely conventional, geometric design in which the initial stage can hardly, if at all, be recognized. I believe the first to discover this phenomenon was Frederic Ward Putnam, who described the development, as he called it, of the hollow, slit feet of Chiriquian (Costa Rican) pottery from a fish form to a purely conventional design (fig. 109). He was followed by others who made studies of similar transitions in other parts of the world. William H. Holmes described the so-called alligator vases of Chiriqui, showing the relations between the alligator design and curious irregular painted forms (see fig. 129, p. 137). Hjalmar Stolpe, and about the same time, Charles H. Read (fig. 110) discussed the relations of human figures and geometrical designs in Polynesian ornaments; Haddon studied the so-called crocodile arrows (fig. 111) and the frigate bird (fig. 112) designs of New Guinea in their gradual transition from fairly realistic forms in which the crocodile and the bird are easily recognized, to geometrical types in which the prototype is entirely obscured. Similar relations are found in the facial urns of prehistoric times, (fig. 113) in some of which we find a perfectly plain and distinct face, while in others there are only a few knobs that, on account of their position, recall the face. George Grant MacCurdy takes us back to Chiriqui where he collected from museum collections series of types beginning with the form of the armadillo and ending with small decorative points (fig. 114). Von den Steinen forms out similar phenomena in the tattooings of the Marquesans. [Illustration: Fig. 112. Designs representing frigate bird and crocodile.] In a few cases the striking similarity of the patterns which contradicts the diversity of names suggests an historical relation between the forms. This is the case, for instance, with the Bushongo antelope and beetle patterns (fig. 115). The resemblance between the realistic antelope head (_a_) and beetle design (_d_) is evident. It is, however, not necessary to assume a transition from the antelope to the beetle design, but the question has to be answered in how far the stylistic form may have moulded the two representations in the same form or, on the other hand, why an ornamental form may have outlines that, on the one hand, express an antelope’s head and, on the other hand, the body of a beetle.[66] [66] E. Torday and T. A. Joyce, Notes ethnographiques sur les peuples communément appelés Bakuba, etc. Les Bushongo, Documents ethnographiques concernant les populations du Congo Belge, Vol. II, number 1, Brussels, 1910, p. 212.