i 9 4 PLANT-BREEDING 



reaching a height of some six feet, with numerous wide- 

 spread branches. Their fruit is relished by cattle, being 

 juicy and nutritious, and not too spiny. The disc-like seg- 

 ments of the stem also contain nutritious food, and this is 

 sometimes made use of, the prickles being softened by cook- 

 ing under the influence of the juice from the cellular tissues. 

 But cooking is an expensive mode of preparation, and thus 

 the thorns prevent the use and culture of the cacti on any 

 large scale. 



From this discussion it is evident that a spineless edible 

 Opuntia would be a most welcome addition to the agricul- 

 ture of the semi-arid West. It could be cultivated without 

 irrigation on the same plains where the spiny forms now 

 occur in the wild state. It would turn deserts into fertile 

 ranches, admitting of cattle raising, and thus ' restoring the 

 lands to human industry. 



The genus Opuntia is very rich in species, many of which 

 are natives of Mexico. Here some kinds occur which have 

 no spines at all, and others in which these organs are only 

 partly developed. The spines of the Opuntia are of two 

 kinds, some being broader, smooth beneath their sharp tips, 

 and of a leafy nature; others are thin, covered all over their 

 length by little hooks, and more of the nature of prickles. 

 It is especially this latter kind which so often makes the 

 Indian figs, when not carefully peeled, disagreeable for eat- 

 ing. Burbank transplanted into his garden as many of these 

 deviating species as he could lay hands on, and began an 

 extensive series of crossings. Their aim was to combine 

 the absence of both forms of spines with the favorable qual- 

 ities of the tree-like kinds of the southern deserts. Of course 

 this could not be reached by a single cross, since numerous 

 qualities have to be considered before a really productive 

 thornless edible variety could be secured. Repeated crosses 

 and selections were required, but the result has ultimately 



