35 



ley. It is possible that tlie tlioruless Iiidiaii-fig cactus of Algiers aud 

 soutbern France could be introduced with profit into the Rio Grande 

 Valley. A similar cactus is grown in the vicinity of Monterey, Mexico, 

 and has been cultivated at Corpus Christi by Dr. William De Ryee and 

 at Santa Gertrudes by Mr. R. J. Kleberg, However, this pear cactus 

 is not frost-proof, like the native species. Dr. De Ryee states that the 

 spines may bo eliminated from the common species by pursuing the 

 same course of treatment as that used in the production of the spine- 

 less form by the Mexican gardeners, who grow it for its superior fruit 

 and not for its excellence as a forage plant. A young shoot or joint of 

 the flattened stem taken before the spines are fully formed is set out in 

 fertile soil. As soon as this has taken root and started to grow, a 

 young cutting from the i)lant is treated in the same way, and so on, 

 continuing for two or three seasons, always planting in rich and well- 

 watered soil. By the third or fourth year the cactus will usually have 

 lost all of its spines, so that there is nothing to prevent its being eaten 

 by cattle. This Mexican cactus might be acclimated by the method of 

 gradual transference each year a little farther north, and also by selec- 

 tion of the most hardy stocks; or, better, the same method of cultivation 

 and improvement might be applied to cuttings of the superabundant 

 Texan prickly ])ear with the view of securing an unarmed form of it for 

 propagation in the arid portions of the State. The experiments wonld 

 necessarily last through a long term of years, because the same care would 

 be required in selecting hardy and drought-resistant spineless forms 

 as in coaxing the plant to repress its spines. If the smooth form is 

 transferred abruptly back to normal conditions of sterile soil and 

 lack of moisture, the spines at once reappear, while both stem and fruit 

 lose whatever points of excellence they may have acquired through 

 cultivation. The experiment would have to be continued long enough 

 for the acquired characters to become in some measure fixed. Such an 

 improvement through cultivation would elevate the pear cactus to the 

 rank of the cultivated plants. The rancher who wished to avail him- 

 self of it would have to grow the spineless forms on good rich soil, and 

 sow the seed over the ranges at intervals of a few years. There would 

 certainly be a return to the normal form in time, just as there is in the 

 case of the carrot, or of the red pepper grown first on cultivated soils 

 aud then allowed to run wild, but if the spineless habit could become 

 sufficiently fixed as a result of growth under improved environment 

 the reappearance of sharp spines when the plant is grown on poor soil 

 might be retarded several years. Such experiments ought to be under- 

 taken, for if thornless cactus of some forage value could be grown in the 

 place of the inedible wild varieties it would prove of immense pecuniary 

 advantage to the stockmen of this portion of the State. A spineless 

 form of the common prickly i)ear of India ( Opuntia dillenii) is there used 

 for forage, and it is reported that good silage has been made from a 

 mixture of cactus and grass placed in the silo in alternating layers. A 



