Page:Popular Science Monthly Volume 1.djvu/695

Rh to serve a most remarkable physiological end in connection with generation. The palpi of the male are furnished with several hooks, and a kind of cup (Fig. 8), while those of the female taper to a point, and are armed at the extremity with a toothed comb, like those at the end of the feet, and with several long, sword-shaped hairs.

But if, at the anterior extremity of the spider, we see in miniature the most perfect enginery of destruction, at its posterior extremity there is an equally marvellous device for the work of construction. If you direct your lens to the abdominal segment, you will observe what is represented in Fig. 10. The projections there seen are called spinnerets, and are contrivances for producing the web. One pair is prominent, the remaining two pairs having the appearance of circlets (Fig. 10, ), and they are all studded over with rows of little microscopic tubes (Fig. 10, b b). From these minute tubes there exudes a glutinous substance prepared in the spider's body, which solidifies into



a fine, strong filament as soon as it is exposed to the air. The microscope has proved that every one of these almost invisible fibres is composed of hundreds of finer ones, just as a ship's cable is formed of minute hempen fibres, while the main strand is spun far more rapidly than the eye can follow the process. The strength thus secured is very great, and the line is not only strong but elastic, like an India-rubber thread. LeuwenhoekLeeuwenhoek [sic], the renowned microscopist, who studied this subject carefully, made some extraordinary statements in regard to the minuteness of these threads. Some spiders, he says, that are not larger than a grain of sand, spin complex cords of which it would take millions to equal in thickness one of the hairs of his beard. If we ask why the mechanism was not simplified so that the animal should pay out only a single line, the obvious reply is that the multitude of finer filaments were necessary for quick drying and the firmest