Note 252 — Chapter XIV

In Biologie, by G. R. Treviranus, vol. ii. p. 302, the following passage occurs:—“If we expose spring water to the sun in open or even closed transparent vessels, after a few days bubbles rise from the bottom, or from the sides of the vessel, and a green crust is formed at the same time. Upon observing this crust through a microscope, we discover a mass of green particles, generally of a round or oval form, very minute, and overlaid with a transparent mucous covering, some of them moving freely, whilst others, perfectly similar to these, remain motionless and attached to the sides of the vessel. This motion is sometimes greater than at others. The animalcules frequently lie as if torpid, but soon recover their former activity.”