SOILS OF THE ARID AND HUMID REGIONS. 417 



belt of high rainfall on the Malabar (western) coast of the 

 Indian peninsula. ' 



The productiveness of the laterite soils seems throughout to 

 be only moderate, yet much higher than would be expected of 

 soils of similar composition in the temperate zones, where the 

 rate of soil-formation is so much slower than in the tropics. 



From the analyses of " coffee soils " from Yarcand in the 

 Sheveroy hills, north of Madras, we learn that coffee does well 

 with a fairly liberal supply of lime (.30 to .44%} and phos- 

 phoric acid, but is satisfied with a much smaller amount of 

 potash than is found in the tea soils of Assam. 



A farther systematic investigation of the soils of India, with 

 simultaneous accurate observations on their depth, subsoil, 

 geological derivation, topographical location and relations to 

 rainfall, could not fail to yield very important practical results. 

 The examination of samples collected and sent in by persons 

 unfamiliar with the proper mode of taking soil specimens, and 

 the information which should accompany them, always in- 

 volves a great deal of uncertainty and waste of labor, and in- 

 clefiniteness of results. 



INFLUENCE OF ARIDITY UPON CIVILIZATION. 



In connection with the facts given and discussed above, as 

 to the relative productive capacity of lands of the humid and 

 arid regions, it becomes of interest to consider what influence, 

 if any, these differences may have had in determining the 

 choice of the majority of the ancient civilizations in favor of 

 countries where nature imposes upon the husbandman, who 

 supplies the prime necessaries of life, the onerous condition of 

 artificial irrigation. 1 



Preference of .-Indent Civilizations for Arid Countries. A 

 brief review suffices to establish the fact of such choice. Aside 

 from Egypt, the permanent fertility of which is ascribed to the 

 inundations of the Nile, we find to westward the oases of the 

 Libyan and Sahara deserts, the high fertility of which has 

 become proverbial and has caused them to be cultivated from 

 ancient times to the present. Similarly, on both sides of the 



1 Verhandlungen tier Deutschen Physiologischen desellschaft in Berlin, Decem. 

 ber 1892; North American Review, September, 190^. 



