Outward Extension of Spinules in Exine of Centrolepis aristata (Centrolepidaceae)

Spinules extend outwards 0.2 to 0.3 μm into the plasmodial tapetum during periods of rapid growth of microspores of Centrolepis. Before and after these intervals spinules commonly protrude only ca 0.05 μm above the surface of the tectum. The extended spinules have a rod shaped core ca 40 nm in diameter. The surface of the core is surrounded by loops ca 30 nm in diameter arranged in a regular pattern.     

Environmental determinants of intraspecific variation in body weight in baboons (Papio spp.)

Mean body weights of baboons differ considerably between populations for both males and females. This paper examines possible environmental causes of these differences. Mean annual rainfall and mean annual temperature are shown to be the two main factors responsible. Mean body weights for both sexes are a quadratic function of rainfall. Possible reasons why this might be so are examined.