CHAP, ii.] of Plants. Dittrochd. 59

organisms was a product of chemical processes induced by respiration, for this had been regarded since the time of Aris- totle as more peculiarly an effect of the principle of life. And now another discovery was made, equally calculated to pro- mote the reference to mechanical principles of those general and important phenomena of life which had hitherto been in- dolently ascribed to the operation of the vital force. It appears to be a matter of indifference whether Professor Fischer of Breslau is or is not to be considered as the true discoverer of endosmose in 1822, for it is certain that it was DUTROCHET' who first studied the subject with exactness, and above all per- ceived its extraordinary value for the explanation of certain phenomena in living organisms. He repeatedly called atten- tion to this value in the years between 1826 and 1837, and endeavoured to refer a variety of phenomena in vegetation to this agency. He had first observed the operation of endos- mose in its mechanical effects in living bodies ; the escape of the zoospores of an aquatic Fungus and the ejection of the sperm from the spermathecae of snails first led him to the hypothesis, that the more concentrated solutions inclosed in organic membranes exercise an attraction on surrounding water, which, forcing its way into the inclosed space, is there able to exert considerable powers of pressure. To Dutrochet

1 Henri Joachim Dutrochet, born in 1776, was a member of a noble family which belonged to the department of thelndre and lost its property during the i \nlution ; he therefore adopted medicine as a profession, and took his degree at the Faculty of Paris in 1806. He was attached to the armies \\\ Spain as military surgeon in iSoS and 1809; but he retired as soon as possible from practice and devoted himself in great seclusion to his physio- logical pursuits, living for some years in Tourainc. lie was made cor- responding member of the Academy in 1819, and communicated his discoveries to that body. Becoming an ordinary member in 1831, he spent the winter months from that time forward in Paris. He died in 184.7 a f ter two years' suffering from an injury to the head. Dutrochct was one of the most successful champions, in animal as well as vegetable physiology, of the modern ideas which displaced the old vitalistic school of thought after

See the ' Allgemeine Zeitung ' for 1847, p. 7^-