Reported here are the organization and activities of Die Vogelschutzwarte am Main, visited by the authors in June 1958. This is one of the seven official West German institutes of bird protection, belonging to one or a few of the provinces. Its main objects are: one, to prevent decrease of any species of birds from the point of view of nature preservation and two, to increase the useful birds, particularly insect-eating small birds, in a simple and least expensive way. It is aimed to raise their density to fifty times as that of present. The main activities are: 1) Studies for artificial propagation of useful birds. Unlike the results obtained in England and Holland, the basic investigations on food, breeding biology, movements, population density, so far made here, showed that nesting-site, not food supply, is the principal limiting fact in their forest birds. 2) Instruction of forest wardens (Forstbeamten) concerning bird propagation. Each station instructs 10 wardens, or 350 in entire State, two weeks a year to have them engaged in bird propagation after returning to their provinces.) 3) Cooperation of its own bird-protection wardens (Vertrauensleuten). Four thousand wardens are said to be working for the Frankfurt, a. M. Station. 4) Necessary control of harmful species of birds. 5) Planning of meetings for students, children and general people to study bird protection, and their visits to the station. The authors express their hearty gratitudes to the Direstor, Dr. S. Pfeifer for his kind arrangement of the visit, and to Dr. Keil for his friendly guidance.
The immature Wistar rats, 35, 40 and 45 days old, received the subcutaneous injections of 30 R. U. 'Hypohorin' and 1000 I. U. 'Serotropin' at an interval of 48 hours, and then the ovaries including oviducts of the treated animals were fixed 14 hours after treatment. They were sectioned and stained for the microscopical observation. Ovulation was induced in every ovary under examination (Figs. 2-3). The number of extruded eggs was 186 in total; they vary from 5 to 36 by individual, being 18.6 in an average (Table 1). Microscopical examination revealed that the extruded eggs in induced ovulation showed the second polar spindle persisting at metaphase (Fig. 4). The evidence presented indicates that the eggs obtained by artificial ovulation in immature rats passed the maturation process in a regular manner. Probably they are capable of fertilization.