197 
are, as a rule, poisonous, though there are believed to be some 
exceptions. 
The protection gained by this spiny armature is increased 
and made more effective by the great readiness with which pieces 
of the stems take root and multiply, if broken off. In this way, 
they come to grow in vast, dense colonies, often to the exclusion 
of almost all other growth, and sometimes so densely as to 
entirely preclude travel among them by large animals. 
the peculiarities which I have mentioned, have de- 
veloped quite a number of uses to which cactuses are put. First 
among such uses we will consider those which relate to the 
furnishing of drinking water for desert travelers in danger of 
perishing of thirst. 
The fact that cattle, fed upon cactus pulp, require no other 
water supply, teaches the thirsting savage to chew and suck this 
pulp. When hecan reach some one of the large barrel-cactuses, he 
employs a more elaborate method. The top of the stem is cut 
off and the soft inner pulp of the body is chopped and broken up, 
and then mashed with a pounder, and finally brought into such 
a state that it can be taken up and the water wrung out of it 
with the hands. It is said that in Mexico, a large cylindrical 
stem-section is sometimes removed, the cut ends sealed up, a 
hole bored in one | the section placed over a fire with this 
hole uppermost, and t ontained water driven off and con- 
densed. A number of area in this process suggest them- 
selves, but it can scarcely be regarded as impossible 
The protective properties of the spines of cactuses are utilized 
in many ways. Cattle hedges are produced by merely dropping 
pieces of the stems in a row, where they quickly take root and 
form an impenetrable barrier. Stems of the organ- ~cactus are 
stems a foot or more in diameter, and often twenty feet or more 
inheight. Adobe walls surrounding gardens are surmounted with 
a growth of spiny cactus which is pretty apt to keep out maraud- 
ing boys. Huts or kraalls are often built wholly or partly of cactus 
stems, and are an excellent protection against the inroads of wild 
beasts and serpents. 
