of the mammillarias, rarely grow higher than half 
a foot; the great majority of the other genera 
have an upright growth of from 18 inches to 6 
feet ; two, Opuntia spinosissima and Cereus repan- 
dus, have usually a height of about 20 feet; and 
one, Cereus hexagonus, commonly attains the 
enormous height of 35 or 40 feet. The multitudes 
of small species creep among the sands and rocks 
and dry forest-grounds of their native countries 
in so vast profusion and with such blood-spilling 
gripes as to render travelling amongst them dif- 
ficult and lacerating ; and the few tall species lift 
their gaunt, grotesque, angular, leafless, spine- 
armed stems far above the surrounding stunted 
vegetation, and form a bizarre and rueful feature 
of a sterile and sun-scorched landscape. 
The cacti occur in greatest profusion within 
the tropical parts of America; and, till quite a 
recent period, were supposed to extend very 
slightly or not at all within the temperate lati- 
tudes. But from the immediate vicinity of the 
city of Mendoza in South America, situated in 
30° of southern latitude, Dr. Gillies has sent to 
the botanic gardens of Britain no fewer than 
twenty-two species; and in the North American 
region of the Rocky Mountains, between 30° and 
40° of northern latitude, Messrs. Douglas and 
Drummond saw many cacti. The common opun- 
tia, however—Opuntia vulgaris, formerly called 
Cactus opuntia—has for centuries been natural- 
ized in the south of Europe, particularly in Spain 
and Sicily; and was introduced thence to Great 
Britain so long ago as toward the close of the 
16th century. 
The cacti abound chiefly on hot dry sandy 
plains, or hot dry rocky districts where plants of 
a less succulent or more perspiring nature could 
nt exist ; and they serve both to afford cooling 
nutriment to man in regions where drink and 
ordinary food cannot be obtained, and to produce 
a vegetable soil on surfaces which, but for their 
growth and decay, would for ever remain arid 
wastes. They possess a singularly tough epider- 
mis, and have very few and merely rudimentary 
stomata ; and, in consequence, are enabled to re- 
tain for a long period such moisture as they can 
collect from rains and dews, and to sustain un- 
hurt the full play of the unclouded tropical sun, 
and the ardent radiation of his calorific rays from 
the surrounding sands and rocks. The common 
opuntia easily inserts its roots in the cracks and 
crevices of the volcanic rocks of Sicily, and readily 
propagates itself over expanses of volcanic sands 
and ashes where not a particle of humus exists ; 
and it has eventually dispread itself over the en- 
tire surface of many a naked hill, and either 
formed, or is in the process of forming, a suffi- 
cient depth of vegetable mould by its decay to 
sustain the most useful forms of vegetation. Se- 
veral of the opuntias are selected by the Spanish 
Americans, on account of their rapid growth and 
their spinous armature, for the formation of 
fences around fields and dwellings; and they 
CACTUS. 
speedily elongate and amass themselves into such 
powerful enclosures as neither man nor beast can 
penetrate. Numerous species of opuntia are fed 
upon by the cochineal insect, in both a natural 
and a cultivated condition; all the species with 
red flowers appearing to be relished by its own 
taste, and the species which are least spiny being 
cultivated for its use in Peru and Mexico; yet a 
species to which botanists have given distinc- 
tively the name of Opuntia cochinillifera, pro- 
bably affords less food to the insect than any one 
of several other species. ‘The insipid juice with 
which the stems of most of the cacti abound is 
a grateful nutriment to the inhabitants of many 
parts of the American tropics; and the fruit of a 
considerable number of species is, in these dis- 
tricts, as much relished for dessert as the goose- 
berry is in Europe, and is profusely used in cool- 
ing drinks for fevers, and is occasionally employed 
as an external application for the cure of ulcers, 
and, in some instances, constitutes a bulky and 
essential article of daily food. The common opun- 
tia covers the hills of Palermo, and produces its 
crops of fruit for the Sicilians, in nearly the same 
manner in which some of the most valuable escu- 
lents cover the choicest fields of our farms, and 
produce daily nutriment to Britain. “The cac- 
tus,” we are told, “was probably introduced into | 
Sicily by the Spaniards. It forms as important 
an article of diet with the inhabitants of that 
island as the potato does with ourselves. 
and is considered very palatable, although stran- 
gers usually find it insipid.” The chief of the 
other species which are most valued for their 
fruit are Cereus multangularis, a plant of South 
America, seldom attaining a height of more than 
9 or 10 inches; Cereus Peruvianus, a red-flowered 
plant of Peru, usually about a yard high; Cereus | 
triangularis, a white-flowered plant of the West 
Indies, usually about a foot high; Cereus Royeni, 
a white-flowered plant of South America, usually | 
about two feet high ; Cereus lanuginosus, a white- 
flowered plant of the West Indies, usually about 
a foot high; Cereus repandus, a gigantic white- 
flowered cactus of the West Indies, usually about 
twenty feet high; Pereskia aculeata, a white-flow- 
ered plant of the West Indies, usually about five | 
feet high ; Pereskia grandifolia, a Brazilian plant, 
about a yard high; Pereskia longispina, a South 
American plant, about four feet high; Pereskia 
portulacefolia, a West Indian plant, usually about 
a yard high; Pereskia Bleo, a rose-coloured flow- 
ering plant of Mexico, usually about five feet 
high; and Cereus speciosissimus, a crimson-flow- 
ered plant of South America, usually about a 
yard high, and producing even in the hothouses 
of Britain a fruit as large as a hen’s egg, with a 
very rich and agreeable, smell, resembling that of 
a pine apple. 
The cacti are very extensively cultivated in 
almost all our hothouses; and they form a chief 
611 
This | 
abundant, cooling, and juicy fruit forms the prin- | 
cipal food of the lower classes for three months, | 
"i aT a = ate oo nt a : 
\ 
