There has been some controversy about whether adult females of social Stegodyphus disperse by ballooning. Here we show that adult Stegodyphus dumicola (Eresidae) Pocock 1898 are able to gain up-lift by releasing a very large number of threads. The threads fan out widely from the spider's body and form a triangular sheet. This previously unknown ballooning mechanism, enables even large spiders to disperse over large distances.

THE air space of the hen's egg and that of the bird's egg in general, and its changes during the period of incubation, are insufficiently known in many respects, in spite of the fact that its phenomena might be of interest for the study of foetal respiration in the chick. Even its origin is not fully known. According to Lataste [1925] its appearance is the result of contraction of the soft parts from the rigid egg shell as the egg cools after having left the mother's body. Evaporation of water from the surface of the shell was considered to increase its volume gradually, but no importance should in his opinion be attached to this regarding its appearance. It is not easy to understand why evaporation of water should not contribute to its appearance as well as to its expansion, the egg being exposed to both influences simultaneously as soon as it has been laid. Lataste's argumentation that reptile eggs with flexible walls have no air space does not disprove this view.There are three properties of the air space which interested us especially: (1) the volume and its changes during the period of incubation, (2) the composition of the gas contained and its changes, and (3) pressure of the gas and its changes.1. VOLUME OF THE AIR SPACE Some figures relating to the volume of the air space have been given by Hasselbalch [1902]. In order to obtain greater quantities of gas the eggs had previously been kept in a thermostat at a temperature of 25 and 380 C.