CHAP, in.] the Movements of Plants. 545 



1788, by Smith in 1790, and by others, but without leading to 

 any discoveries respecting the nature of the irritability. Dal 

 Covolo's famous essay on the stamens of the Cynareae (1764) 

 produced no absolutely final result, but it contained some par- 

 ticulars which threw light on the mechanical laws of these 

 movements of irritability. Koelreuter, who studied these 

 objects in 1766, thought less of discovering a mechanical ex- 

 planation of them, than of finding arguments in the irritability 

 of the stamens for the necessity of insects to pollination. An 

 entirely new kind of movement was discovered by Corti in 1772 

 in the cells of Chara, which is now known as the circulation of the 

 protoplasm ; this form of movement in plants appeared at first 

 to bear no resemblance whatever to the phytodynamic pro- 

 cesses then known, and it was not brought into connection 

 with them till a long time after ; on the contrary an erroneous 

 idea soon began to prevail, that it was a real rotation of the 

 sap, as understood by the early physiologists ; this idea held 

 its ground till far into the iQth century, and being combined 

 with mistaken notions respecting the movements of latex, was 

 developed by Schultz-Schultzenstein into the doctrine of the 

 circulation of the vital sap. For a time indeed Corti's dis- 

 covery was forgotten, and had to be reproduced by Treviranus 

 in 1811. A somewhat similar fortune attended the discovery 

 of the movement of the Oscillatorieae by Adanson in 1767, 

 which misled Vaucher into pronouncing them to be animals. 



3. Imperfect as were the theoretical efforts of the i8th cen- 

 tury in this branch of botanical study, yet they aimed at tracing 

 the various movements back to the play of physical forces. 

 But in the closing years of the century another order of ideas, 

 injurious to the healthy progress of science, made its appearance 

 in this, as in other parts of botany and zoology. Even the 

 majority of those who had no sympathy with the nature-philoso- 

 phy and its phraseology, believed that there was in organised 

 bodies something of a special and peculiar nature ; because the 

 attempts made to explain the phenomena of life by mechanical 



