234 VEGETABLE SUBSTANCES. 



application, is of course thrown off with the tunic or 

 outer coat, and does not in any way protect the co- 

 tyledon or side lobes of the seed, which come up 

 in the form of leaves, and in which the eggs of 

 the fly are then deposited. By some cultivators 

 these leaves are powdered with quick-lime as soon 

 as they show themselves above ground ; a plan 

 which appears the most rational for preventing the 

 mischief. One of the easiest remedies against it, 

 however, is recommended by Neill, to sow thick, 

 and thus ensure a sufficiency of plants both for the 

 fly and the crop. As soon as the rough leaves are 

 a little developed the danger from the insect depre- 

 dator ceases. 



Turnips, if carefully cultivated, attain to a very 

 great size in this country, though appearing insig- 

 nificant when compared with the gigantic root of the 

 Roman naturalist. Tull* speaks of some weighing 

 as much as nineteen pounds, and of often meeting 

 with others of sixteen pounds. In Surrey, a Swedish 

 turnip, the seed of which had been sown in July, was 

 dug up in October, 1828, which weighed twenty-one 

 pounds, and was one yard in circumference. t But 

 these are far surpassed by one which was pulled up 

 in 1758 at Tudenham, in Norfolk, and which weighed 

 twenty-nine pounds. J In No. 360 of the Philoso- 

 phical Transactions, we find a curious calculation made 

 by Dr Desaguliers, on the rapid increase of a turnip 

 root. One ounce of turnip-seed was found by him to 

 contain between fourteen and fifteen thousand single 

 seeds ; therefore, one seed would weigh one-fourteen 

 or one fifteen-thousandth part of an ounce ; and 

 assuming its growth to be always uniform, a turnip- 

 seed may increase fifteen times its own weight in a 

 minute ! By an actual experiment made on moss or 



* Tull'i Horse-Hoeing Husbandry. 



t Gard. Mag. t Campbell's Pol. Survey, vol. ii. 



