BOOK XVII. XVIII. 9i-.\i.\-. 94 



Even this department of knowledge is not to be 

 despised, nnr put in the last class, inasmuch as to each 

 kind of plant shade is either a nurse or else a step- 

 mother — at all events for tlie shadow of a walnut tree 

 or a stone pine or a spruce or a siher fir to touch any 

 plant whatever is undoubtedly poison. 



XIX. The question of raindrops falling from trees spaeingoj 

 can be settled briefly. With all tlie trees which are "'''"• 

 so shielded by the spread of their foHa<re that the rain- 

 water does not flow down over the tree itself tlie drip 

 does cruel injury. Consequently in this enquiry it 

 will make a great deal of difterence over what space 

 the soil in which we are going to plant causes the 

 various trees to grow. In the first place, hillsides in 

 themsehes require smaller intervals between the 

 trees. In places exposed to the w ind, it pays to plant 

 trees closer together, but nevertheless to givc the oHve 

 verv wide spacing, Cato's opinion" for Italy being that 

 olives should be planted 25 or at most 30 feet apart ; 

 but this varies with the nature of the sites. The oUve 

 is the largest of all the trees in Andalusia ; in Africa, 

 however, so it is stated — the guarantee for this state- 

 ment will rest with the authorities who make it — 

 there are a number of trees called ' thousand- 

 pounders ', from the weight of oil that they produee 

 in a year's crop. Consequently Mago has prescribed a 

 space of 75 feet all round, or in thin, hard soil exposed 

 to the wind, 45 feet at least. Andalusia however 

 reaps most abundant crops of corn grown between 

 the olives. It will be agreed that it shows shame- 

 ful ignorance to thin full-grown trees more than a 

 proper amount and hasten them into old age, or 

 to cut them down altogether, by doing which 

 the persons who planted them frequently manifest 



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