AGRICULTURAL TEXT-BOOK. 213 



of starch, for tho purpose of sustaining breath and heat, not for 

 building up the body. Pcreira estimates that 1 Ib. of butcher s 

 meat is equal to 10J- Ibs. of potatoes. In consequence, those 

 who live sololy upon them are obliged to consume inordinate 

 quantities; and the stomach, habitually distended with the great 

 bulk, becomes unnaturally enlarged, and incapable of digesting 

 concentrated food. This was shown during the Irish famine, 

 when more than an equivalent of corn meal, or other nitrogen 

 ous food, being much smaller in quantity, entirely failed to sus 

 pend that craving which the stomach feels when empty. 



At the same time, in consequence of the great yield per aero, 

 much more nourishment can be produced from a given area of 

 8oil by this crop, than by any other except perhaps corn. The 

 following example will prove this (Knapp) : 



From one hectare of land (= 2.471 acres) there were pro 

 duced under similar circumstances, 



3,400 Ibs. wheat, 2,800 Ibs. rye, 2.200 Ibs. peas, 38,000 Ibs. potatoes, ot 

 3.036 do 2,538 do &quot; 2,980 do 9,500 do 



after deducting the amount of moisture. In this quantity of 

 dry produce there is contained : 



In wheat. In rje. In peas. In potatoes. 



Nitrogenous matters, 570 Ibs. 440 Ibs. 560 Ibs. 950 Ibs. 

 Starch, 1,590 &quot; 1,196 &quot; 780 &quot; 6,840 &quot; 



Mineral ingredients, 90 &quot; 62 &quot; 60 &quot; 323 &quot; 



And in consequence, when the Irish learnt to depend on this food 

 alone, cultivating chiefly with the spade, population very rapidly in 

 creased ; the land was subdivided into portions too small to be profita 

 bly applied to grain for where one acre of potatoes would sustain a 

 family, it would require many acres of grain to do the same, together 

 with the necessary cattle and when this crop failed, there was nothing 

 to fall back upon, starvation ensuing in consequence. In India, the 

 same results follow the dependence on rice, in many respects a very 

 similar food. It may be laid down as a general principle, that the more 

 highly civilized, intelligent, and prosperous nations are, the greater 

 amount of nitrogenous vegetable and animal aliment do ihey con 

 sume ; and in wearing out the soil of a single farm, or of a State, 

 the decline is gradually from muscle-forming to heat -producing pro- 



