288 VEGETABLE SUBSTANCES. 



quantity of seed being regulated according to the des- 

 tination of the onions, whether they are to be drawn 

 young or to remain for bulbing. The plants begin 

 to bulb in June, increasing in growth till the middle 

 of August, when the necks shrink and the leaves 

 decay : they are then in a fit state to be drawn, and 

 preserved for the winter store. 



A method of improving the size of onions by 

 transplanting them was recommended by Worlidge, 

 so early as the beginning of the seventeenth century, 

 in his ' Systema Horticultures ;' and this practice has 

 lately been revived with great success by some emi- 

 nent horticulturists. 



The theory on which it is founded is extremely 

 ingenious. JRvery plant which lives longer than one 

 year, generates the sap or vegetable blood which will 

 elaborate the leaves and roots of the succeeding spring. 

 In bulbous roots this reserved sap is deposited in the 

 bulb, which, in a great measure, it composes. Now 

 the store which is thus formed varies considerably in 

 the same species of plant, according to the particular 

 circumstances under which it is raised. Thus the 

 onion in the south of Europe accumulates a much 

 greater quantity in a single season, under a greater 

 degree, and longer duration of heat, than is afforded 

 by our colder climates, and therefore it acquires, in a 

 given time, a much larger size. Mr Knight was 

 induced by these observations to suppose that two 

 short and variable summers in England might, per- 

 haps, be equal in effect to one long and bright season 

 in Portugal; and, accordingly, he attempted a method 

 of culture which has proved his inference to be cor- 

 rect. In pursuance of this plan seeds of the Portugal 

 onion were sown in spring very thickly, on a poor 

 soil, and in a shady situation. Under these circum- 

 stances, the bulb in the autumn had attained scarcely 

 beyond the size of a large pea. The bulbs were then 



