146 VEGETABLE SUBSTANCES. 



adapted for this culture has already been sufficiently 

 indicated. The sets are planted in lines from twenty to 

 twenty-four inches apart, either in drills or by the dib- 

 ble, at intervals of from twelve to fifteen inches. The 

 proper season for planting the main crop is from the 

 middle to the end of March, and a peck of seed po- 

 tatoes is usually required to plant a bed of twelve 

 feet by thirty-two. In field culture eighteen bushels 

 are planted in one acre. The young plants are kept 

 free from weeds, and when they are about half a 

 foot or a foot high, some earth is drawn around the 

 lower part of the stern ; little or no farther care is 

 required till the taking up of the crop. The plants 

 are suffered to remain until the roots attain to their 

 full growth. This state is indicated by the stalks 

 beginning to decay, which usually takes place at the 

 commencement or latter end of October, when the 

 roots should be dug up for the winter store. Some 

 careful cultivators pinch off the blossoms as they ap- 

 pear on the plant : the good effects of this practice 

 have been very often proved, it being supposed that 

 the weight of the tubers of each plant is increased an 

 ounce in consequence, or considerably above a ton 

 per acre.* The cause of this result has been thus 

 explained ; the fluid or sap gives sustenance alike to 

 the tuber and blossom, and therefore, if a portion be 

 diverted from the formation of the blossom, it will 

 be exerted for the enlargement of the root. 



This plant may be propagated also from cuttings 

 or layers of the green shoots, and from seeds. The 

 first is not at all advantageous for any culture, ex- 

 cept in some instances, when it is required to mul- 

 tiply as quickly as possible a rare sort. 



The tubers obtained from seeds are at first very 

 few and very small, and therefore seed cultivation 

 is by no means advisable to ' the grower ' of po- 



* Hort. Trans, vol. i. 



