10 Introduction. 



field before it was in the earth, and every herb of the field 

 before it grew. We consider the narrative of the creation of 

 man to be a type of that of all other living beings ; the dust was 

 formed into the image of each, and the breath of life imparted to 

 it gave a material being. The vital principle is the same in kind 

 through all gradations of existence. It has six properties, which 

 we discover by the different series of phenomena each presents 

 to us. These are Irritability, Mobility, Vital Affinity, Vivifi- 

 cation, Sympathy and Sensibility. The first four are common 

 to plants, which possess little if any of the last two, as they want 

 the nervous system, the instruments of their manifestation. Irri- 

 tability, or Excitability, is that power capable either of acting or 

 being acted upon ; it is the main-spring of the whole movement. 

 Mobility is the power of motion ; by it the sap ascends and de- 

 scends, and the sensitive plant is enabled to shrink from the 

 touch. Vital affinity is so called in contra-distinction to chemi- 

 cal affinity, which last unites bodies in a multiple proportion and 

 only two at a time ; the former unites a dozen at once, and in all 

 proportions. Vivification is the vitalizing or imparting of life. 

 They possess these properties in a very extensive degree : a root 

 will last an immeasurably longer time than a man ; we have 

 authentic evidence of seeds living over 4000 years. 



Plants subsist on inorganic matter ; animals on nothing but 

 organic. The vegetable kingdom is the purveyor of the animal, 

 and this furnishes their great distinction. It was formerly thought 

 that Instinct was denied altogether to plants, but the following 

 anecdote will show the error of such a conclusion. " I was one 

 day," says Aime Martin, "sitting under the shade of those 

 acacias called Mimosa Eburnea, whose thorns are as white as 

 ivory. On a sudden I saw the deep shade in movement, and 

 giving place to a flickering light let in upon me. The foliage 

 seemed at once to have withered. A dark cloud passing over- 

 head caused the phenomenon. When the cloud was past, and 

 the sky had become serene, the foliage became reanimated and 

 resumed its freshness. This acacia flourishes in the burning 

 clime of India. My first solution of the cause of the sudden 

 withering of the leaves was, that the habit of the tree was only 

 to give light in the clear shade of the sun ; and that, by a kind 

 of foresight, it refused its shade to the earth when it was not 

 needed. On more exact observation I became convinced, that 



