The male of one of the bugs, _Euchistus variolarius_, has a black spot on the end of the abdomen--a spot that is not present in the female. Foot and Strobell crossed a female of this species to another bug, _E. servus_, that lacks the spot in both sexes. The daughters had no spot, the sons a faint spot less developed than in _variolarius_. These inbred gave (in F₂) 249 females without a spot, 107 males with a spot, and 84 males without a spot. The results are explicable on the view that a single dominant Mendelian factor, not-sex-linked, causes the spot in the males, but the presence of the gene in the female produces no effect. The effect, therefore, is sex-limited, _i. e._, its expression is determined by the rest of the complex male or female. The very important breeding experiments carried out by Goldschmidt on varieties of the gipsy moth should be referred to in this connection, but as I have recently reviewed these results in the paper on gynandromorphs written in collaboration with C. B. Bridges,[19] I need only refer to that account here. [Note added April 21, 1919.] Shortly after the preceding paper was finished a theses by A. Pézard on the secondary sexual characters of birds reached me. In it the author gives an account of a number of experiments that he has made with poultry and with pheasants. His description of the changes that take place after castration are more exact and more detailed than any other so far recorded; but in general the results obtained by Pézard, through castration, are the same as those that had been obtained by others. Castration of 4 male silver pheasants are reported. No change in the plumage results, although the changes that take place in the comb and wattles are the same in kind as those observed in fowls. The sexual instincts and peculiarities of the voice and their belligerency are also lost. Similarly 4 golden pheasants that were operated on gave the same results. Three pheasants with mixed plumage (_Phasianus colchicus_) were examined. Their testes proved, on histological examination, to be imperfectly developed. It is not evident what relation existed between the facts and the mixed plumage. The suggestions made by Pézard seem inadequate to cover the cases. Testicular tissue transplanted into castrated cocks whose comb, wattles, etc., had undergone retrogressive changes brought about a return to the normal conditions after an interval during which the implanted nodules had begun to regenerate.