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IN an examination of stock cultures of the red-rust flour beetle, Tribolium castaneum:1 Herbst, in connection with experimental population studies, a certain individual was found which possessed eyes completely lacking black pigment in certain ommatidia. The eyes of this form appeared white or pearly when contrasted with the eye of a normal Trib oliumn, which is entirely black. This suggested at once that the unusual eye pattern might be due to some kind of heritable variation, since the failure of pigment to develop seems to be an effect quite commonly produced by gene mutation. In order to study this character genetically, a number of pupae were segregated from the stock culture and sexed (for technique see Park, 1935) and then set aside and kept in a virginal condition until examined. Out of this group of sexed pupae one pearl eyed male and one pearl eyed female were found which appeared exactly, with respect to eye pigmentation, like the original pearl eyed beetle. These two pearl forms were mated together and their progeny studied. The progeny were all pearl eyed like their parents and when bred with themselves for the purpose of multiplying the pearl stock gave all pearl eyed forms. It seemed patent, on the basis of these results, that this eye abnormality was an inherited characteristic and certain genetic crosses were made to determine the mode of inheritance of the mutation which is. to the best knowledge of the

A gene, designated "paddle," is described for the flour beetle Tribolium castaneum, and shown to be inherited as a single, sex-linked recessive. The somatic effect of the gene is to cause varying degrees of fusion of the three segments constituting the antennal club. In addition, male mutant beetles show a reduction in the number of antennal segments from the eleven characteristic of the genus to a modal number of nine.

ALTHOUGH scattered observations on the life span of many vertebrates and invertebrates are legion, the accurately Collected mortality. data necessary for the construction of a life table are, apart from mnan, few indeed. For the insect group, life tables in complete or abridged form have been published for representatives of four orders: the Orthoptera (Blatta orientalis), the Lepidoptera (Telea polyphtemis and Acrobasis caryae), the Diptera (Drosophtila melanogaster and various of its mutants), and the Coleoptera (Tribolit am1 coonfusumt). Reference to the first three orders will be found in the papers of Pearl and AMiner (1935 and 1936); to the last order in Pearl, Park alcd Mliner (1941). The present paper reports a life table for another, and hitherto little studied, flour beetle, Tribolimi qnadens. The details of life table construction, the significance of the life table for many pleases of population biology and a review of the literature dealing with mortality in infra-human populations are not considered pertinent for this short paper. If interested, the reader can find further information in Bodeniheinier (1938), Dublin. and Lotka (1936) and Pearl (1940). The flour beetles (Tribooliulml cojifusutm and Triboliamn;^ castaneum) are proving to be appropriate organisms for experimental populations studies (see Ford, 1937, and Park, 1941). It is hoped that, as more backg-round data 1 I wish to express my sincere thanks to Dr. Alfred J; Lotka, of the Metropolitail Life Insurance Compally, whose advice has been inv-aluable. I am also greatly iiidebted to Mr. Albert W. Buzicky, of The University of Miimesota, for furnishilgg me with a culture of Triboltm macdens as well as for a ilnunber of suggestions. This investigation has beeni aided by a grailt from the Dr. Wallace C. adll Clara A. Abbott Meioriml Funid of the University of Chicago.

In this paper are presented life tables for males and for females of the beetle Tribolium confusum Duval, living in regularly renewed fresh flour. The Tribolium life curves resemble in their fundamental pattern human life curves more closely than do those of any other organism for which life tables have as yet been computed. They have at the beginning of life in the imago stage a component corresponding in the time and quantitative relations of its incidence to the infant mortality component of human life tables.