THE VEGETABLE KINGDOM. 377 



CHAPTER II. 



THE CIRCULATION IN PLANTS. 



THE more we study nature the grander does she appear. 

 Science, by penetrating her secrets, often shows us that 

 hidden and imposing forces exist where we only see inertia. 

 The obscure vitality of plants, brought to light by the gen- 

 ius of naturalists, sometimes manifests itself to our eyes in 

 unexpected power. 



Plants, like animals, have a circulation. It is to that 

 universal genius, Claude Perrault, at one and the same time 

 physician, architect, and naturalist, that we owe the dis- 

 covery of this phenomenon. The sap, which is in fact the 

 blood of the plant, circulates through its vessels by means 

 of a power possibly greatly exceeding that which drives the 

 blood through the arteries of an elephant. The celebrated 

 Hales made a very curious experiment on this subject. 

 Having fitted a long tube to the stem of a young vine 

 which he had severed, he saw this fluid rise forty -four feet 

 high. These results appearing very extraordinary to the 

 French physiologists, they soon repeated the experiments 

 of the English philosopher, but they were greatly astonished 

 to see that they were within the mark. In fact, De Can- 

 dolle, who was one of the last to move in the matter, noticed 

 that the force with which the sap rises in the vessels of the 

 plant is equal to the pressure of two atmospheres and a 

 half, a force which enormously exceeds, and indeed al- 

 most doubles, the results obtained by the Canon of Wind- 



