412 STERILITY AN ADVANTAGE. 



light, it was difficult to find which was the male and 

 which the female element, as based upon analogies 

 to the animal kingdom. 



The extent to which hybridization can be carried 

 is limited. Thus hybrids can, and have been, ob- 

 tained from plants of an entirely distinct genera; 

 and yet these were sterile, and not capable of pro- 

 ducing a new genus of plant. The Creator has wise- 

 ly ordered this, else confusion would take the place 

 of order. Plants of two species often produce a hy- 

 brid ; these are generally sterile, or productive only 

 by impregnation from the pollen of one of their 

 parents, to which type they will revert in the next 

 generation. But this is one of the most fertile 

 causes of the production of varieties. Thus, while 

 species seem to be immutable, varieties are as muta- 

 ble as the individuals from which they originate. 



Sterility is not always a disadvantage, but some- 

 times positively the opposite, as regards cultivation. 

 For example, such varieties of fruits as are destitute 

 of seed are for that very reason eminently desirable, 

 because the demand for nourishment which would 

 have been made by the seed is not felt, and thus a 

 much larger crop of fruit may be realized with less 

 exhaustion to the tree. 



In the Annals of Natural History, M. Thwaites 

 said, " The most eminent physiologists seem to be ar- 

 riving at the opinion, that the fertilization of the 

 ovule, as it is termed, consists in the union of a 



