1. A new apparatus is described for measuring visual intensity discrimination over a large range of intensities, with white light and with selected portions of the spectrum. With it measurements were made of the intensity DeltaI which is just perceptible when it is added for a short time to a portion of a field of intensity I to which the eye has been adapted. 2. For white and for all colors th...

The noble false widow spider Steatoda nobilis is a globally invasive species with implications for public health and possibly native ecosystems. Here, we report on case of predation protected vertebrate, pygmy shrew Sorex minutus in Britain. importance novelty this are: (1) the third documented S. preying vertebrate five years, suggesting that small vertebrates are likely to be more frequent co...