112 THE POPULAR SCIENCE MONTHLY. 



the process ; but the jointed stem usually answers the purpose of 

 leaves under such conditions far better than any thin and exposed 

 blade could do in the arid air of a baking desert. And therefore, 

 as a rule, desert plants are leafless. 



In India, for example, there are no cactuses. But I wouldn't 

 advise you to dispute the point with a peppery, fire-eating Anglo- 

 Indian colonel. I did so once, myself, at the risk of my life, at a 

 table d'hote on the Continent; and the wonder is that I'm still 

 alive to tell the story. I had nothing but facts on my side, while 

 the colonel had fists, and probably pistols. And when I say no 

 cactuses, I mean, of course, no indigenous species ; for prickly 

 pears and epiphyllums may naturally be planted by the hand of 

 man anywhere. But what people take for thickets of cactus in 

 the Indian jungle are really thickets of cactus-like spurges. In 

 the dry soil of India, many spurges grow thick and succulent, 

 learn to suppress their leaves, and assume the bizarre forms and 

 quaint jointed appearance of the true cactuses. In flower and 

 fruit, however, they are euphorbias to the end ; it is only in the 

 thick and fleshy stem that they resemble their nobler and more 

 beautiful Western rivals. No true cactus grows truly wild any- 

 where on earth except in America. The family was developed 

 there, and, till man transplanted it, never succeeded in gaining a 

 foothold elsewhere. Essentially tropical in type, it was provided 

 with no means of dispersing its seeds across the enormous expanse 

 of intervening ocean which separated its habitat from the sister 

 continents. 



But why are cactuses so almost universally prickly ? From 

 the grotesque little melon-cactuses of our English hot-houses to 

 the huge and ungainly monsters which form miles of hedgerows on 

 Jamaican hillsides, the members of this desert family are mostly 

 distinguished by their abundant spines and thorns, or by the irri- 

 tating hairs which break off in your skin if you happen to brush 

 incautiously against them. Cactuses are the hedgehogs of the 

 vegetable world ; their motto is Nemo me impune lacessit. Many 

 a time in the West Indies I have pushed my hand for a second 

 into a bit of tangled " bush," as the negroes call it, to seize some 

 rare flower or some beautiful insect, and been punished for twenty- 

 four hours afterward by the stings of the almost invisible and 

 glass-like little cactus-needles. When you rub them they only 

 break in pieces, and every piece inflicts a fresh wound on the 

 flesh where it rankles. Some of the species have large, stout 

 prickles ; some have clusters of irritating hairs at measured dis- 

 tances ; and some rejoice in both means of defense at once, scat- 

 tered impartially over their entire surface. In the prickly pear, 

 the bundles of prickles are arranged geometrically with great 

 regularity in a perfect quincunx. But that is a small consolation 



