STATISTICS OF THE ORDER CRUCIFERAE, 399 
jects, we would prepare the way for them by stating a few sim- 
ple facts in reference to the distribution and habitats of plants. 
We cannot now enter into the cut bono part of the question, this 
we must leave for another occasion. We fear we have already 
exceeded our bounds. 
Statistics of the Order Cructrera@, with the Periodicity, Dura- 
tion, Habitats, and Range of the British Species of this Order. 
The Crucifere are as remarkable for the number and utility of 
the species which the Order comprehends, as for their extensive 
horizontal and vertical range, and for the variety of habitats in 
which they are found. The Order is chiefly European. Its census, 
given by Professor De Candolle in 1821, is subjoined, as adopted 
by Dr. Lindley, viz. 344 species are found in Europe, from the 
shores of the Arctic Ocean to those of the Mediterranean; 45 
belong to the southern or African shores of the latter-named sea ; 
318 are said to belong exclusively to Asia; 133 belong to the 
southern hemisphere, including New Holland and South America; 
53 belong to North America and the adjoining islands; and 
35 are common to various parts of the world. Since 1821 the 
number of known plants has been doubled. lf we double the 
Crucifere known, then the estimated number known now (1856) 
will be 1740. But if we assume that the number of Phznoga- 
mous plants, described or discovered, is about 100,000, the number 
of Cruciferous plants might be estimated at upwards of 4000, as- 
suming that the Crucifere are 1-25th of the Phenogamous spe- 
cies. In the British islands the number of Phenogamous plants 
(see last edition of the London Catalogue) is 1871, and if we 
allow 29 for the excluded species, 1400; the number of Crucifere 
in the same catalogue is 70, and therefore the Cruciferous plants 
amount to 1-20th of the Phenogamous vegetation of Great Bri- 
tain and Ireland. As these plants abound in Europe more than 
in the warmer regions, probably 1-25th is the proportion they 
bear in the general or universal Flora of the whole known world, 
or they constitute 1-25th part of the vegetable kingdom, and 
consequently amount to about 4000, estimating the number of 
known species at 100,000. We know that 70 species are found 
in the British Isles, and we have reason to believe from the his- 
