240 CAUSE OF STERILITY. 



value for its delicacy, and probably approaches nearly to the 

 wild state of the plant; of Plantains few, except the wild and 

 crabbed sorts, are seedful. The remedy for this appears to be, 

 the withholding from such plants aU. the sources from which 

 their succulence can be encouraged. If, in consequence of 

 any predisposition to form succulent tissue (on which the excel- 

 lence of fruit much depends), the organizable matter of the 

 plant be once diverted from feeding the seed to those parts in 

 which the succulence exists, it will continue, by the action of 

 endosmose, to be attracted thither more powerfully than to 

 any other part, and the effect of this will be the abortion of 

 the seed : but a scanty supply of food, an unhealthy condition 

 of the plant itself, or withholding the usual quantity of water, 

 will all check the tendency to luxuriance, and therefore will 

 favour the developement of the seed, whose feeble attracting 

 force is, in that case, not so liliely to be overcome by the 

 accumulation of attracting power in the neighbouring parts. 

 Thus we see that Pine-apples are more frequently seedful 

 under bad cultivation, than in highly kept and skilfully 

 managed pineries. Abstraction of branches, m the neigh<- 

 bourhood of fruit, has also been occasionally found favourable 

 to the formation of seed; evidently because the food that 

 would have been conveyed iato the branches, having no outlet, 

 is forced into the fruit, and thus reaches the seed. ' 



Another cause of sterility is the deficiency of pollen in the 

 anthers of a given plant, as in vegetable mules, which usually 

 partake of the spermatic debility so well known in similar 

 cases in the animal kingdom. It has often been found 

 that sterility of this kind is cured by the application, to the 

 seedless plant, of the vigorous pollen of another less debilitated 

 variety. 



In some plants, such as Pelargoniums, when cultivated, the 

 anthers shed their pollen before the stigma is ready to receive 

 its iafluence, and thus sterility results. All such cases are 

 provided for, by employing the pollen of another flower. (See 

 Sweet in the Gardener's Magazine, vii. 206.) 



An unfavourable state of the atmosphere obstructs the 

 action of pollen, and thus produces sterility. PoUen will not 



