THE VEGETABLE KINGDOM. 385 



the circulation in the plant to the same cause which makes 

 the blood move in the capillary vessels of animals. 



The greatest botanists of our time follow the author of 

 " General Anatomy." De Candolle thinks that the ascent of 

 the sap must be ascribed to the vital contraction of the tis- 

 sues ; its cause he considers is allied to life. Achille Kichard, 

 after a general view of the whole power of vegetable circu- 

 lation, compares it to that of insects. 1 



Schultz of Berlin, who has so deeply studied this func- 

 tion, considers it as essentially due to the vital action of the 

 vessels. By means of the microscope we can, according to 

 him, see these contract in order to propel the fluid which 

 they contain. The learned Prussian even perceives, in ref- 

 erence to this phenomenon, a great analogy between plants 

 and certain inferior animals of the class of worms. 



After such authorities it is impossible to hesitate any 

 longer, and it must be admitted that the circulation in 

 plants is essentially due to a vital cause. Then follow, as 

 accessory powers, the various actions of heat, capillary at- 

 traction, endosmosis, and electricity. With the aid of the 

 microscope any person can convince himself of the truth of 

 everything here stated. In viewing with this instrument 

 plants in which the sap contains colored granules, we see 

 these pass rapidly along in the capillary vessels. Professor 



1 Achille Richard, so illustrious as a savant, and of so worthy and noble a char- 

 acter, often reverts in his work to the vital power in plants. On this subject he 

 expresses himself, when speaking of the circulation in plants, in the following au- 

 thoritative manner : " Here, as in most other functions of animals and plants, we 

 must admit an unknown, powerful, active force, the result of organization and 

 life, which is their immediate, indispensable agent, and which is designated vital 

 force." Richard, Botanique et Physiologic Vegetale, Paris, 1846, p. 238. 



