32 THE BOOK OF NATURE STUDY 



compensate for his loss on root crops and hay. It is very important 

 to correlate the variety of crops which country children see around 

 them with the peculiarities of our climate. The economic geographer 

 will no doubt say that the fact that England and the lowlands 

 of Scotland are characteristically " polycultural " is due to more 

 than one cause, but climate is certainly one of these, and one that 

 is worth emphasising. 



Our climate is very variable, but the variations are small, and 

 it is possible to discount the minor climatic variations by a judicious 

 variety of crops. In the general case the risk of prolonged, severe 

 drought is too small to make it necessary to arrange any method 

 of bringing water to the crops. With this condition one would 

 naturally compare others. In the Great Plains of North America 

 as one travels westward one approaches a region where the rainfall 

 is just sufficient for crops in normal seasons. From a variety of 

 causes the cultivated crops are limited, wheat largely predominat- 

 ing ; in other words the district is largely " monocultural." If a 

 series of seasons with good rainfall occur, more and more land is put 

 down to wheat. A series of dry seasons may then occur, and as 

 the farmer has no other crops to fall back upon total ruin may 

 result. If a farmer only grows wheat ; if he knows that every 

 now and again there will come years of prolonged drought ; if in 

 those years the rain that does fall comes in heavy drenching 

 downpours, when the water runs off his land before the poor 

 plants have received much benefit, what would the members of 

 the class suggest doing ? In some such way one might lead up to 

 the question of irrigation, obtaining from the class examples of 

 countries where it is practised. Conversely, show them that if we 

 know that irrigation is practised in such and such a country, from 

 this very fact we may deduce a good deal as to the climate of the 

 country. 



RAINFALL AND VEGETATION. From such conceptions we 

 want to travel farther in order to investigate the problem as 

 to the effect of drought, occasional or continued, on vegetation. If 

 no rain falls for some time and water is not supplied artificially 

 what becomes of the plants ? Neglected lawns may often be 

 found to help us to answer this question. Careful persons water 



