FORESTRY OF WEST AFRICA. 263 



the Royal Gardens, Kew, who will be glad to recom- 

 mend the books most suited to each Colonial garden, 

 and the best and least expensive way of procuring 

 them. He will also give assistance towards naming 

 dried specimens of the plants of the Colony for the 

 Superintendent, provided the latter keeps up a her- 

 barium and a proper correspondence in plants, &c., 

 with the Royal Gardens. 



The following extracts on the disadvantages and 

 advantages of vegetation, from Dr. Parke's ' Practical 

 Hygiene,' may be here of comparative interest : — 



" Vegetation produces a great effect on the move- 

 ment of air. Its velocity is checked, and sometimes 

 in thick clusters of trees or underwood the air is 

 most stagnant. If moist and decaying vegetation be 

 a coincident condition of such stagnation, the most 

 fatal forms of malarious diseases are produced. 



" Vegetation may thus do harm by obstructing the 

 movement of the air ; on the other hand, it may guard 

 from currents of impure air. The protective influence 

 of a belt of trees against malaria is most striking. 



"Herbage is always healthy. In the Tropics, it 

 cools the ground, both by obstructing the sun's rays 

 and by aiding evaporation ; and nothing is more de- 

 sirable than to cover, if it be possible, the hot sandy 

 plains of the Tropics with close-cut grass. 



"Trees should be removed with judgment In 

 cold countries they shelter from cold winds, in hot 

 they cool the ground ; in both they may protect from 



