Serology and Animal Systematics

Abstract

The Libby photronrefleetometer has been applied to the study of Crustacean sera, in measuring the turbidities developing as a result of the interaction of precipitin antisera and a variety of antigens. In comparison with the ring test the photronreflectometer technique has many advantages for it compares antigens over the whole range of their reactivity with their corresponding antisera and proves to be a more quantitative, more discriminating, and more adequate method of precipitin testing. Unlike the ring test the photron''er. measurements, provided the whole reactive range of the antisera is included, require no independent proof of comparability of the amts. of the various antigens tested. The results of testing 14 anti-Crustacean sera with the sera of common Crustacea are generally in accord with their systematic positions, but give in addition a first quantitative estimate of the relative positions to each other of the following spp.: Homarus ameri-canus and H. vulgarus, Callinectes sapidus, Carcinus maenas, Cancer borealis, C. irroratus, C. pagurus, Menippe mer-ccnaria, Geryon quinquedens, Ocypode albicans, and Maia squinado. Of special interest are the results indicating (1) that Homarus americanus and H. vulgarus are about as distinct as the different spp. of Cancer are to each other; (2) that Geryon quinquedens representing the Goneplacidae lies nearer to the Xanthidae represented by Menippe mer-cenaria than to any other family tested. With regard to the degree of serol. differentiation of the spp. of a genus, the genera of a family, and the fams. of an order, the results so far obtained with the photron''er. in Crustacea, Insecta, Mollusca, Pisces, Aves and Mammalia are in general agreement. Only in Aves are the degrees of serol. differentiation a little less than in the other animal groups. The indications are therefore that such tests may provide a kind of serological "yardstick," correlated with the rank of the systematic category.