Carl Düsing (1884) on the regulation of the sex-ratio

In three publications in 1883 and 1884 Carl Düsing of Jena gave a mathematical account of the influence of natural selection on the sex ratio based on the same argument that Darwin had advanced in The Descent of Man (1871). The argument thus became quite well known, being included in the principal books on the subject around the turn of the century, as well as in the Encyclopaedia Britannica, references to Düsing being given. By 1930, when Fisher gave a verbal account of the argument in The Genetical Theory of Natural Selection, he saw no need to give references, and no other book of the period treated the subject, as a result of which Düsing's contribution became lost to view. We here give the important paragraphs of Düsing's mathematical account, translated into English.