Chap, ii.] of Plants. Dntrochet. 509 



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 1 

 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 the Indre and lost its property during the 

 revolution; he therefore adopted medicine as a profession, and took his 

 degree at the Faculty of Paris in 1806. He was attached to the armies in 

 Spain as military surgeon in 1808 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 Touraine. He was made cor- 

 responding member of the Academy in 181 9, 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 1847 after 

 two years' suffering from an injury to the head. Dutrochet 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 

 1820. See the ' Allgemeine Zeitung' for 1847, p. 780. 



