45 



of the mountains and plateaus of the interior give density to the 

 air and cause it to flow down the slopes eastwtard and south- 

 ward toward the sea. As it descends it becomes absorbent and 

 hence the winters are dry and cool. In the summer, the in- 

 terior air is heated and, pressed by the cooler air from the sea, 

 becomes ascensive. As the moist air flowing inland from the 

 sea rises, it becomes precipitant, and hence the summers are 

 warm and moist. In north China notably it is the July and 

 August rains that are the foster parents of the crops. 



The moisture borne inland by the ascensive summer winds 

 and precipitated on the slopes of the interior, on the barrier 

 mountains, and on the bordering plateaus, bears back from them 

 to the lowlands a constant burden of new soil material, a means of 

 natural fertilization. By this fresh material the alluvial plains 

 are built up and built out seaward, and their fertility is nat- 

 urally renewed wherever such accessions take place. In the 

 northern tracts there is added an annual film of dust from the 

 deserts. Thus even the deserts make some compensation for 

 their barrenness. 



But the extraordinary preservation of the fertility of China 

 is due mainly to the unusual care and intelligence of the Chinese 

 people in the management of their soils and the handling of 

 their plants. The plants they cultivate may almost be said 

 to be treated individually, as animals are by other peoples. 

 Seed is rarely sown broadcast. Even cereals are planted in 

 hills or rows. Fertilizers also are often planted with the seed 

 or applied to the hills tho often also spread broadcast. The 

 fields are carefully prepared and scrupulously tilled. Inter- 

 estingly enough, plant reciprocities have been discovered, no 

 doubt by pure empiricism and without even now knowing the 

 reasons that lie back of the observed efifects. One often sees 

 rows or hills of wheat alternating with beans, mustard alter- 

 nating with peas, and various other alternations of legumes 

 with cereals and other plants, thus securing the simultaneous 

 cooperation of plants well fitted to one another. We seek the 

 mutual good offices of plants by rotation, but the Chinese go 

 a step further and secure this by inter-planting. The results 



