ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 323 



two-jointed exopodite, and an endopodite, biarticulate or undivided, 

 transformed into a copulatory organ. It is reduced to one piece (fused 

 sjmpodite and exopodite) in the female. There is also a discussion of 

 Asellus communis. J. A. T. 



Sex-intergrade Strain of Cladocera. — Arthur M. Banta {Proc. 

 Soc. Exjjer. Biol. Medicine, 1916, 14, 3-4). After 130 parthenogenetic 

 generations of Simocephalus vetulus, in the course of which only females 

 occurred, there being no males nor sexual eggs, the 131st generation 

 showed, in addition to normal females, both males and many sorts of 

 sex intergrades. " There occurs practically every gradation from the 

 entirely normal female with a full complement of female secondary 

 sex characters ; thi-ough female intergrades of all sorts ; hermaphrodites, 

 with various combinations of secondary sex characters ; and male 

 intergrades of various rank ; to normal males with all the primary and 

 secondary sex characters distinctly and strongly male." J. A. T. 



Sex Intergrades in Cladocera. — Arthur M. Banta {Proc. Nat. 

 Acad. Sci., 1918, 373-9). Unmistakable intermediate sex forms are 

 known in Riddle's hybrid pigeons, Goldschmidt's hybrid gipsy moths, 

 and Banta's Cladocei-a. They are not sex mosaics but sex intergrades. 

 In Simoceijlialus vetuJus the occurrence of clearly marked sex intergrades 

 is rare ; it is not so unusual in Daj^hnia longispina, where several strains 

 have been studied. In these, however, male sex intergrades (i.e. inter- 

 grades with testes) are almost or quite lacking, and males are rare, 

 whereas in the Simocephalus vetulus sex intergrade stock normal males 

 are abundant and male intergrades are common. Sex intergrade pro- 

 duction would seem to be the result of a disturbed balance, a condition 

 which is a struggle of two nearly equal factors or sets of factors, the one 

 making for maleness, the other for femaleness. The resnlt of this 

 struggle of factors is the development of individuals ostensibly male in 

 part and female in part, and obviously intermediate in part — but as a 

 whole distinctly intermediate in sex characters. The facts suggest that 

 maleness and femaleness are not complete and mutually exclusive states, 

 but that sex is relative. J. X. T. 



Selection with a Pure Line of Cladocera. — Arthur M. Banta 

 {Proc. Soc. Exper. Biol. Medicine^ 1919, 16, 123-4). A study of long- 

 continued selection upon several parthenogenetic pure lines (clones) of 

 three species of Cladocera, using their reactiveness to light as a basis for 

 selection. In most of the lines the results, though suggestive, are 

 inconclusive; or there is clearly no effect of selection ; or (in two lines) 

 the results even suggest slight differences in the reverse of an effect of 

 selection. But with one line of Simocephalus vetulus the result of 

 selection was pronounced and convincing. This line was subjected to 

 selection for a period of 54 months, covering 181 generations of descent. 

 In the final ten generations the strain selected for greater reactiveness 

 to light had a reaction time less than one-third as large as that for the 

 strain of the same line selected for reduced reactiveness to light. 



J.A.T. 

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