The explanation of these recurring phenomena is that a great cloud or distended stream of meteors revolves around the sun in a period of 331years, and that one portion of the elliptical orbit intersects that of the earth.
In aquatic plants the leafstalk is sometimes distended with air, as in Pontederia and Trapa, so as to float the leaf.
If it becomes distended the ball is pierced to liberate the gas and again lightly closed.
As compared with the majority of Acari, ticks are of large size, distended female specimens of some of the species measuring half an inch or more in length, while even the newly hatched young can hardly be regarded as microscopical.
It is not quite so thick as a goosequill when distended, and nearly a foot in length.