346 VEGETABLE SUBSTANCES. 



ever quarter they blow, are always wafted across the 

 expanse of the Atlantic; and the latter lying near 

 the dry and sultry shores of Africa, and, of course, 

 subjected to more changes of season and a higher 

 temperature. There is also some difference in the 

 soil. Whether it be the decomposition of the rock, 

 or saline particles, brought by the same pestilent 

 wind that withers the south of Italy and Sicily with 

 the sirocco, it is well known, that under the artificial 

 earth (brought originally from Sicily) which forms 

 the soil of Malta, there gathers a crust; and that if 

 the earth be not trenched, and this crust removed at 

 the end of a certain number of years, it ceases to be 

 productive, or the produce becomes so bitter, that it 

 is not healthful. St. Michael's has no such disad- 

 vantage; the soil there is native and fertile, and de- 

 posits nothing calculated to injure its fertility, or im- 

 pair the qualities of its produce. 



The oranges of the two islands are such as one 

 would expect from those differences: the Maltese 

 orange is large, the rind is thick and spongy, the 

 glands that secrete the volatile oil are prominent, the 

 pulp is red, and there is a trace of bitterness in the 

 taste; while the St. Michael's orange is small, the 

 rind is thin and smooth, the glands less prominent, 

 the volatile oil in smaller quantity, and the lighter 

 coloured pulp more sugary and delicious. Some 

 allowance must no doubt be made for the original 

 differences of those oranges, regarding them as 

 having come in the manner stated by Galessio; but 

 they have now been long enough in both islands for 

 having their qualities modified by the different cli- 

 mates and soils. 



The modifications produced by differences of soil 

 and climate, in the same vegetable, are among the 

 most important inquiries in the science of plants; 

 and they are at the same time among the most 



