138 WORLD-POWER AND EVOLUTION 



to exist in a mild, endemic form. It apparently rises to virulence 

 when the vitality of a large section of the Community falls to a 

 low ebb. In this respect it resembles famine fever, whose dreaded 

 consequences were well exemplified in Ireland during the potato 

 famine about 1845. The same is true of cholera and influenza, 

 and of tuberculosis, as we have seen from the German statistics. 

 In China nothing weakens the people like great floods, which 

 drown the rice-fields and bring famine. Hence it is highly prob- 

 able that the sequence in the first half of the fourteenth century 

 was something like this: great solar activity, climatic extremes, 

 floods in China, failure of the rice crop, famine, pestilence, and 

 death. Thus climatic extremes may have been the cause not only 

 of 25,000,000 deaths in Asia, but of another 25,000,000 which 

 are reported to have occurred in Europe at that ill-fated time.'^j 



The importance of such climatic vicissitudes can be seen even in 

 our own time. Although now the extremes are not equal to those 

 of the fourteenth century and still less to those of earlier histor- 

 ical times and of the prehistoric and glacial periods, they cause 

 terrible devastation. Even in our own country large areas in 

 western Kansas, New Mexico, and other dry regions have been 

 settled, abandoned because of drought, resettled, and in some 

 cases even abandoned again and then settled for the third time. 

 Many a farmer has had to pack up all his goods and trek across 

 the country in search of a new home. In India the British gov- 

 ernment has spent hundreds of millions in famine relief and in 

 building railroads to bring food and canals to bring water in the 

 hope of reducing the deaths due to failure of the crops when the 

 monsoon rains are deficient. Yet hundreds of thousands of people 

 still die of starvation or of diseases induced by scarcity of food. 

 In China, too, both droughts and floods still bring disaster as 

 they have done for centuries. Even as I write I have before me 

 a news clipping saying that a million people are even now, 

 in May, 1918, in danger of starvation. Even in so progressive a 

 country as Australia the effect of variations in rainfall is terrible. 



