Fecundity in the fowl is shown to be inherited in strict accord with the following Mendelian plan:-- 1. Observed individual variations in fecundity depend essentially upon two separately inherited physiological factors (designated L_{1}, and L_{2}). 2. _High_ fecundity is manifested only when both of these factors are present together in the same individual. 3. Either of these factors when present alone, whether in homozygous or heterozygous form, causes about the same degree of _low_ fecundity to be manifested. 4. One of these factors, namely L_{2}, is sex-limited or sex-correlated in its inheritance, in such way that in gametogenesis any gamete which bears the female sex-determinant F does not bear L_{2}. 5. There is a definite and clear-cut segregation of high fecundity from low fecundity, in the manner set forth above. From the standpoint of eugenics it is pointed out that these results furnish a new conception of the mode of inheritance of fecundity, and may be helpful in suggesting a method of attacking the same problem for man. ETHNIC PSYCHOLOGY AND THE SCIENCE OF EUGENICS. (Abstract.) By Prof. Enrico Morselli, _Director of the Clinic for Mental and Nervous Diseases, Genoa University_. All natural varieties or races of mankind differ, not only by their physical, but also by their mental, characters. There exists, therefore, an "Ethnic Psychology" which, along with "Ethnic Somatology," constitutes the complete Science of Anthropology or the Natural History of Man. This must describe and classify races and populations under a double aspect--physical and psychical. The psychical characters of races are in part _original_, and in part acquired through _adaptation_. These persist in a race as long as such mesological adaptation lasts; they vary with modifications of the conditions of life, including social activities and inter-racial relations. In mixed unions, amongst different races, there are always some which are more vigorous, biologically and mentally, more fully developed, which impress their characters upon their descendants. For the vitality and well-being of mixed or metamorphic populations a certain amount of difference amongst the parent races is necessary, but too great a difference is injurious to the offspring. The offspring of mixed unions present in their psychology a _mixture_, again a _combination_ or fusion of the mental characters of the parent races: sometimes certain psychical characters of a race become the _dominant_ characters. All ethnic groupings have their destiny marked out by the grade attained in _the human psycho-physical hierarchy_. Nevertheless, it is necessary that each race or nation, when it knows its contribution to the development of universal civilisation, should contemplate the preservation of its own ethnic type. Differentiation amongst peoples is an indispensable factor in human progress.