Among the great groups of the cactus clan the Pincushion, the Hedgehog, the Giant Sahuaro, and the Bisnaga, or Barrel Cacti, have retreated before civilization. The first named cannot endure close grazing of the ranges, nor trampling by stock, nor being continually dug up and carried away from their native habitats. They are rapidly disappearing from their original haunts. This, notwithstanding the fact that they are the most highly evolved of all cacti. The Giant Cactus is too proud, too dignified to fight or to offer resistance; only his size saves him from destruction. He reproduces very slowly; from some areas he is clearly disappearing, though in others he is making some progress. Before the inroads of civilization, the Hedgehog and the Bisnaga (Barrel Cacti) though strongly fortified are slowly receding, gradually retreating from their far-flung outposts to their native habitats, where they are better able to defend themselves. Even their strong armor cannot withstand the attacks of man in his efforts to convert them into sordid cash. But the _Opuntia_, the Prickly Pears and the Cholla, advance guards of the great cactus invasion from Mexico northward, are the only members of the Fantastic Clan to withstand the inroads of civilization and the only cacti that have prospered and increased in numbers, notwithstanding man’s activities. Man has cut them down, and they have grown up again in greater numbers; he has grazed them with his stock, and they have spread over the prairies, mesas, foothills, and _bajadas_; he has transplanted them to new environments and transported them across the seas to new lands, and they have driven him out of his own home and taken his fields away from him, and have grown up to his very doorstep, almost closing up his home. On the southwestern deserts his close grazing of the ranges has made impossible prairie fires, the great enemy of the cacti, and this has spread Prickly Pears and Cholla over the ranges and carried them to the uttermost parts of the desert, where they have taken root and created new plants again. As a result of all this the Cholla have increased a hundredfold on the deserts and foothills in less than half a century, and in time they threaten to become a menace to mankind.