that those that immediately precede do not cover such 

 as succeed them. Sometimes they are placed alternately 

 on two opposite and parallel lines ; sometimes thjey are 

 distributed by pairs, that cross each other at right 

 angles; sometimes they are ranged on the angles of 

 polygons, circumscribed on ' the branches, and so dis- 

 posed that the angles of the inferior polygon correspond 

 with the sides of the superior : at other times, they 

 ascend the whole length of the stalk and branches, on 

 one or more parallel spiral lines. 



Ye sceptics, can you inform me why plants are dis- 

 posed with so much art ? You will, perhaps, deny that 

 plants imbibe the dew by their inferior surface ! But 

 what would you say, were one to inform ycu, that 

 among leaves, exactly resembling each other, and taken 

 from the same tree, such as have been steeped by their 

 inferior surfaces in vessels of water, have continued 

 green for the space of whole weeks, and even months ; 

 whilst those that have been placed, by way of experi- 

 ment, with their upper surface in the water, perished in 

 a few days ? 



x Herbs that are always immersed in the thickest beds 

 of dew, and that grow much faster than trees, have their 

 leaves formed in such a manner, that they pump in the 

 moisture nearly alike by both surfaces, sometimes more 

 copiously by the upper ones. 



Observe lastly, that die inferior surface of the leaves 

 of trees is commonly less smooth and glossy, and of a 

 paler colour, than the opposite surface. This remark- 

 able difference between the two sides of the leaf, suffi- 

 ciently indicated that they have different uses. 



3. By a mechanism which is very simple, the root 

 forces itself into the earth ; the brancnes shoot out on 

 each side; the leaves expose their superior surface to 

 the open air; and their inferior surface to the earth, or 

 the iniK-r part of the plant. Sow a seed the contrary 

 way, you will observe the radicle and little stalk to bend 



