The casual observation at the registration of the personal history of feeble-minded individuals that 50 per cent. of the birth dates fall within only fourteen weeks of the year (New Year, carnival, and wine harvest) has aroused the desire to deal with the seasonal incidence of the begetting of the feeble-minded on the basis of as much material as possible. For this purpose the author's census of feeble-minded school children, which took place in the year 1897, and referred to the years 1886-90 inclusive, seemed specially suited. Originally (in 1901) a curve was plotted in which all the 8,186 feeble-minded and idiotic children were included whose exact birthdays were known, and this curve was compared with the total curve for that period. (Schweiz. Statistik 112 Liefg.) The latter was constructed in the following manner from the whole number of births (934,619) which occurred in these eleven years:--The general daily average was taken as 100, and the daily average for each month was expressed proportionately. Thus numbers above 100 show a daily birth frequency above the average, while for numbers below 100 the reverse is the case. The curve for the 8,136 feeble-minded persons was constructed in a similar way, and thus a comparison with the general population producing them was made possible. Subsequently (1910-11), in order to secure homogeneous material, the first and last years were left out, since by including them, owing to the non-agreement of the school year and the astronomical year, the earlier months (January-April) were much weighted. By this restriction of the material dealt with the number of feeble-minded is reduced to 7,759, but the material for each separate year is more homogeneous. Distributed between 2,922 days (eight years), the daily production of the feeble-minded is 2.648, the corresponding total number of births of the years 1882-89 ls 677,083, or 231.7 per day. 1.14 per cent. of all births are included in the figure for the feeble-minded. If one treats the total number of births for each month as well as the number of births of feeble-minded according to the method described above, and used by the Federal Statistical Bureau, two curves are produced which diverge considerably from each other in particular months. On the whole the curve for the feeble-minded (thick line) is flatter than the curve for the total. Especially striking are the drop in May and June (corresponding to the procreation period from the 25th July to the 23rd September) and two peaks rising above the "total" curve. One of these is slight, yet distinct. It refers to the months of birth, July and August, corresponding with the procreation period from the 24th September to the 24th November. More conspicuous is the second peak of the curve for the feeble-minded from October to December, otherwise a time poor in births.