WITH his usual clearness, Prof. Oscar Hertwig sums up the situation as regards the rdle of the nucleus in heredity. After o stating the foundations of fact on which theories of heredity and development must be built, he enters upon a careful discussion of the important question whether the nucleus is the sole vehicle of heritable qualities. As Fick put's it, Has the nucleus a “Vererbungsmonopol”? The author defends against all-comers the “Hertwig-Strasburger (1884) hypothesis of the localisation of the idioplasm in the nuclear substances,” and his arguments are put with much force. They are seven in all, the three best being the equivalence of ovum and spermatozoon as regards nuclear material, the precise partition of nuclear substance in karyokinesis, and the reduction which obviates an accumulation of nuclear material. The case is argued with fairness, and the difficulties which abound are considered carefully, the general conclusion being that the 1884 hypothesis is consistent with a large series of important facts, and that no well-established fact is inconsistent with it.
Der Kampf um Kernfragen der Entwicklungs- und Vererbungslehre.
By Oscar Hertwig. Pp. iv + 122. (Jena: G. Fischer, 1909.) Price 3 marks.