Tropical Forests 



Such colonies as Sierra Leone are amongst the oldest 

 possessions of Great Britain, so that it does seems strange 

 that, in spite of the extraordinary fertility of the soil, or 

 rather on account of it, plantations have very seldom 

 been successful. The abundant vegetation and moist 

 atmosphere produces a climate which is quite unsuitable 

 for Europeans and even for natives. Both management 

 and labour are apt to become expensive and unprofitable 

 under such conditions. Nor has any planter any reason- 

 able expectation of living until his plantations pay. 

 The improvement during the last few years has been, 

 however, of the most astonishing character. 



The fact that a mosquito carries the germ of malaria 

 from one fever-stricken patient to those as yet unaffected, 

 has made it possible almost to exterminate malaria in 

 some places, and to reduce the death-rate enormously. 

 Perhaps the most striking instance of the advantage of 

 Sir Patrick Manson's great discovery is the fact that the 

 death-rate at the works for the Panama Canal has been 

 reduced amongst the white employees to 16.71 per 

 thousand.^ This district was notorious as amongst the 

 most deadly to Europeans of all climates in the world. 



Besides this great discovery, the history of sleeping 

 sickness is beginning to be understood. The tsetse-fly 

 is said to convey the blood-parasite or trypanosome from 

 man to the crocodile, and possibly back from the croco- 

 dile to man. There has not, however, as yet been 

 devised any method of exterminating either tsetse or 

 crocodiles.^ 



Even in West Africa, the mere fact that the land is 

 steadily coming under real control by the white man, 

 enormously alters the prospects of the future. When 

 there is real security for life and property, both the 

 native population and the amount of cultivation will 

 increase enormously. 



The first destruction of virgin forest for crops of any 



322 



