THE CACTUS 169 



under the most adverse conditions of soil and 

 climate, they remain absolutely smooth. One 

 other step of progress and, we may confidently 

 predict, the factors for spininess will be so com- 

 pletely eliminated from the germ plasm that the 

 spineless opuntias will breed true from the seeds. 



Even then it must not be expected that the 

 seedlings in any given case will reproduce all the 

 good qualities of the parents ; any more than the 

 seedlings of cultivated varieties of apple or pear 

 or peach will duplicate the qualities of their 

 parents. We have seen that the seedlings of the 

 thornless blackberry are not precisely like the 

 parent form. But they all are thornless. Such 

 will be the case, ultimately, with the spineless 

 opuntias. 



And it must be obvious that when this condi- 

 tion is attained, the experiment of developing 

 the opuntias in any direction will be greatly 

 facilitated. With many varieties of spineless 

 opuntias in hand, each one absolutely free from 

 the tendency to revert to the spiny condition, 

 we shall be able to carry forward experiments 

 in crossbreeding and selection through which 

 any desired quality may be accentuated and 

 developed. 



At the present time, for example, the spineless 

 opuntias are somewhat lacking in protein con- 



