182 PHYSIOLOGICAL BOTANY. 



at least when growing in its native home ; also, that 

 of the two general modes, self, or cross, she greatly 

 prefers the latter. 



450. What are the reasons for this preference? 

 The solution of this inquiry has engaged the attention 

 of many skillful investigators, until it seems to be 

 proved that the offspring of cross-fertilization are as a 

 rule decidedly superior in size, vigor, and variety, 



