CHAPTER I. 



VITAL FORCE. 



Me. Andeew Knight asserted that, in the course of his 

 numerous experiments, he had never been able to trace the 

 existence of anything like sensation or intellect in plants, but 

 that they always appeared to be influenced by the action of 

 surrounding bodies, and not by any degrees of sensation and 

 passion analogous to those of animal Hfe. This seems to have 

 led to the belief that they do not even possess a vital principle, 

 but are mere chemical laboratories. 



One writer ventures to call a plant a porous system — endowed with 

 no mtality other than the power of forming Cytohlasts," and arranging 

 cellules after a definite type {Gardner in Phil. Mag. xxviii. 432). Even 

 here it is admitted that some vitality exists ; for the arrangement of 

 cells, or in other words the construction of plants, each after its kind, 

 out of cells, implies vitality of a high order, although the writer seems 

 to have meant that a plant is little more than a hag of quaternary 

 compounds, and to have overlooked the fact that a plant when dead is 

 a porous system as much as when alive. Nee dens intersit is however a 

 favourite maxim with a certain class of modern writers, although nee 

 absit would appear to be more consistent with all we know of the 

 living world. 



But many discoveries have been made since the days of 

 Knight, and a body of facts, showing the existence of high 

 vitality, if not sensation, among plants, has been collected, 

 with which he was wholly unacquainted. So that it is not too 

 much to say, that the vegetable kingdom is now known to stand 

 at least as high in the scale of life as the inferior orders of the 

 animal kingdom. 



* A Cytoblast is the vital centre round which the cell and all its contents is even- 

 tually formed. 



