474 pliny's NATURAL HISTORY. [Book XVII. 



incessant quivering of its leaves : while that of the alder is very 

 dense, but remarkably nutritive to plants. The vine affords 

 sufficient shade for its wants, the leaf being always in motion, 

 and from its repeated movement tempering the heat of the sun 

 with the shadow that it affords ; at the same time too it 

 serves as an effectual protection against heavy rains. In 

 nearly all trees the shade is thin, where the footstalks of the 

 leaves are long. 



This branch of knowledge is one by no means to be despised 

 or deserving to be placed in the lowest rank, for in the case of 

 every variety of plant the shade is found to act either as a 

 kind nurse or a harsh step-mother. There is no doubt that 

 the shadow of the walnut, the pine, the pitch-tree, and the fir 

 is poisonous to everything it may chance to light upon. 



CHAP. 19. THE DROPPINGS OF WATER FROM THE LEAVES. 



A very few words will suffice for the water that drops from 

 the leaves of trees. In all those which are protected by a 

 foliage so dense that the rain will not pass through, the drops 

 are of a noxious nature. 92 In our enquiries, therefore, into 

 this subject it will be of the greatest consequence what will 

 be the nature developed by each tree in the soil in which we 

 are intending to plant it. .Declivities, taken hy themselves, 

 require smaller 93 intervals between the trees, and in localities 

 that are exposed to the wind it is beneficial to plant them 

 closer together. However, it is the olive that requires the 

 largest intervals to be left, and on this point it is the opinion 

 of Cato, 94 with reference to Italy, that the very smallest in- 

 terval ought to be twenty-five feet, and the largest thirty : 

 this, however, varies according to the nature of the site. Tho 

 olive is the largest 95 of all the trees in Beetica : and in Africa 

 — if, indeed, we may believe the authors who say so— there 

 are many olive-trees that are known by the name of milliariae, 96 



92 This is quite a fallacy. Even in the much more probable cases of 

 the upas and mangineel, it is not the fact. 



93 Theophrastus, De Causis, B. iii. c. 8, says, that trees that grow on 

 declivities have shorter branches than those of the same kind growing on 



plains. 94 D e ^ e ^ ust - c - 16 - 



95 This assertion is doubtful; at the present day, in Andalusia, the 

 palm, the poplar, and many other trees are much larger than the olive. 



96 " Thousand pounders." This, as Fee remarks, is clearly an exag- 

 geration. 



