Pepper.] ^^ [:March 6, 



trees have not the inconveniences of some other hardy trees of a slightly 

 less rapid growth, but also useful for draining, such as plane trees, to 

 which are ascribed (?) many cases of conjunctivitis and keratitis, preva- 

 lent in Algeria, Tunisia and throughout the East generally.* 



Frequently malaria is not due to the soil on which a village or farm 

 is built, but to the neighborhood. In this case a heavy curtain of euca- 

 lypti interposed is always useful and often sufficient to arrest the disease. 

 Of course the swamp, or whatever be the nature of this infectious soil, 

 must not be too extensive or pestilential, and the curtain must be of suffi- 

 cient extent and thickness. 



The eucalypti form open forests, free from under- 



Thev form open , , ,, ^ ^ ^ i. ^ ^, ■ t i_ 



forests brush, that great temptation to the mcendiary shep- 



herd, who sacrifices health and well-being to a scant 

 resource in actual pasturage for his flocks (see above the eflfect of burn- 

 ing down trees). If the subsoil be compact, the roots return to the sur- 

 face ; if permeable, they remain sometimes deep enough to allow a few 

 scant and coarse grasses to grow between and under their shade, if the 

 trees are ftir enough apart. 



The seeds are light and fertile and readily dissemi- 

 Their seeds pro- nated by the wind, thus propagating their species and 



extending plantations. 

 A permanent The foliage is perennial ; its benefit to the atmosphere 



ijenefit to tiie (hygrometrically, electrically and antimiasmatically) 



atmosphere. 



is permanent. 

 Tiiev are killed Besides, many species are killed with difficulty, and 



with difficulty. when destroyed above ground by axe or saw send out 



numerous shoots from the stump ; at first easily broken 

 ofi", but finally firmly fixed, and during the first three years or so giving 

 leaves similar to those of j^oung trees of their age ; that is, lighter in color, 

 more flexible, sticky, cordiform, etc., and possessed of greater antimias- 

 matic virtue than the leaves of older trees. 



It is well known that the protection of land against 



A great protec- wind by an obstacle interposed between it and the 



'"linstwind wind is directly proportional to the height of the 



obstacle and approximately to twenty times that 

 height. Therefore, eucalypti protect a much wider tract than most other 

 trees against strong or otherwise harmful winds, such as the blighting 

 sirocco. With a height of forty metres thej' protect a strip of four fiftlis of 

 a kilometre in width, the highest indigenous trees not protecting more 

 than half this surface. The height to which eucalypti rapidly attain is, 

 therefore, a sufficient reason for preferring them to other trees, except some 

 Acacitc, Mimosoe, to protect land against winds. Alternate rows of euca- 

 lypti of appropriate species can be judiciously cut down near the ground 



*At Boufarik the great improvement in public healtli is due to plane trees, and 

 mainly to the thorough draining of the marsh on wliich the village is built, and where 

 hundreds of colonists lie buried. 



