NATURAL ARRANGEMENT. 



499 



The whole order is preeminently European ; 166 species are found in the north and middle of Europe, and 

 178 on the sea-shores of the Mediterranean ; 45 are found between Mogadore and Alexandria : 184 in the 

 countries of the East, that is to say, Syria, Asia Minor, Tauria, and Persia ; 99 in Siberia ; 35 in China, Japan, 

 and India ; 1(5 in New Holland and the South Sea islands ; 6 in the Mauritius and adjacent countries ; 70 at 

 the Cape ; 9 in the Canaries ; 2 in Saint Helena ; 2 in the West Indies ; 41 in South America : 48 in North 

 America ; 5 in Kamtchatka and the bordering islands ; and finally, 35 are common to several parts of the 

 globe. From this it appears that there are about 100 species in the southern hemisphere, and about 800 in the 

 northern: or, if they are considered with reference to the zones of temperature, 205 are natives of the frigid 

 zone of the northern hemisphere ; 30 of the whole of the tropics ; 548 of the temperate zone of the northern 

 hemisphere ; and 86 of the southern. The forty-first degree of north latitude may be considered the equa- 

 torial line of Crucifera, about half being found on one side of it, and half on the other. Their station is very 

 variable ; many inhabit open sandy places, some form the vegetation about the limits of the perpetual 

 snows of lofty mountains, and many follow the footsteps of man through all parts of the world. 



The useful qualities of the turnip, the radish, the rape, and the cabbage and its multiform varieties, are all 

 well known. The greater part of the order consists of plants possessing high antiscorbutic powers. These ap- 

 pear to depend upon a certain acrid, volatile, oily principle, the chemical nature of which is imperfectly known. 

 It is particularly abundant in the seeds of mustard and the roots of horseradish, and the leaves of Z/epidium 

 latiiblium, which latter exercise a violent influence upon the organs of digestion. The same sort of acrimony, 

 but in less degree, is found in the herbage of the scurvy-grass and the roots of the radish, which act much 

 more mildly when taken inwardly ; thus, when any cruciferous plants are found to be eatable, either from 

 culture or other circumstances, it is to be understood to depend upon a reduction of this acrid principle. The 

 exciting powers of this last are what render the horseradish, the scurvy-grass, and others, so remarkably 

 useful as antiscorbutics ; they are also believed to possess diuretic and diaphoretic properties. It is to be 

 remarked that Crucifera are always eatable when their texture is succulent and watery, as in the roots of the 

 radish and the turnip, and the leaves of the cabbage tribe. A further diminution of the acrid principle is 

 produced by blanching. Cruciferae are said ta possess a greater share of azote than any other tribe of plants ; 

 as is apparent in their fetid smell when fermented. The embryo of all the order abounds in oil, whence many 

 species are employed with much advantage for expressing, either for eating or for feeding lamps. Some 

 of the species are extremely beautiful and fragrant, as the Stocks, the Gillyflowers, the Hesperides, the 

 Candytufts, and many others. The Hutchinsias, Drabas, Cardamines, &c., are among the most interesting of 

 alpine plants. Almost all the species are propagated by seeds, but some of them grow by cuttings, and the 

 perennials by division. 



