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ncral about three or four o'cloclc, and closes again 

 about nine or ten in the morning, These flowers will 

 perform their vigiiiae, if set in a phial of water within 

 doors for several mornings successively. Sometimes 

 they are quite closed, from their utmost state of ex- 

 pansiori; in Jess than a quarter of an hour, 



1G. From what has been said, it plainly appears 

 t"hat there is a considerable agreement between plants 

 and animals, as well with regard to their nutrition as 

 to the structure of their parts. Some extend this far. 

 ther, and think there is something in plants answerable 

 to respiration in animals. They suppose the spiral 

 fibres to be in, the place of lungs, and to serve this 

 very purpose: that in each of these there is a spiral 

 lamina, which is extended or contracted, as it is im- 

 pelled this way or that by the elastic air it includes : 

 that these fibres ascending strait through the trunk,, 

 are dispersed through ail the branches, and thence in. 

 to the leaves, where they an- woven together in a kind 

 of net-work. By this means the more subtle parts of 

 the air are strained through those spiral fibres, to keep 

 the juices of the plant fluid, and perhaps to supply them 

 with nitre or aether, to assist their fermentation. 



The air enters vegetables various ways, by the trunlf, 

 leaves, roots, and branches. For the reception as 

 well as expulsion of it, the pores are very large in some 

 plants. So one sort of walking canes seem full of 

 large pin- holes, resembling the pores of the skin in 

 the ends of our fingers. In the leaves of the pine, if 

 viewed througii a glass, they make an elegant show, 

 standing as it were in rauk and file, throughout the 

 length of the leaves. 



Air vessels are found in the leaves of all plants, and 

 in many are visible to the naked eye. For on break. 

 ing the chief fibres of the leaf, the likeness of a fine 

 woolly substance, or rather of curious, small cobwebs 

 may be seen to hang at both the broken ends. Now 

 these are the fibres of the air vessels, loosed from the/r 

 spiral position, and drawn out in length. 

 H 3 



