POLLINATION. 291 



over until the following season in order to effect any crosses. 

 The longevity of pollen is little understood. That of some 

 species will keep much longer than others. It is supposed that, 

 as a rule, it will not keep beyond a few days or weeks. If the 

 pollen is to be kept, the anthers should be picked just before 

 ready to burst and laid upon paper in a warm, dry and shady 

 place until they dry up and the pollen is all discharged. The 

 anthers must then be removed, and the pollen is securely wrap- 

 ped in dry paper. If it is to be kept long it will probably be 

 better to place it in small, closely cork-stoppered vials. It 

 should be kept in a uniform temperature. 



Methods. All perfect flowers those which contain both 

 stamens and pistils must be deprived of their anthers before 

 the pollen is discharged, to prevent self-fertilization. This 

 removal of the anthers is called emasculation. It is performed 

 before the flower opens, and therefore before any foreign pollen 

 could have reached the stigma. In some flowers, as in the 

 tomato, Fig. 95, ths stigma protrudes even before the petals are 

 fully grown and emasculation must be performed very early. 

 Even if the stigma is not mature, there is a chance that pollen 

 will adhere to it and persist until conditions are fit for its 

 growth. 



The flower is generally emasculated by pulling out the anthers 

 with pincers, but some large anthers can be hooked out easily 

 by a very small crochet hook or by a pin bent to a minute hook 

 upon the point. 



It is many times a tedious operation, how- 

 ever, to pull out the anthers without crushing 

 them, and thus distribute some of the pollen. 

 A surer and better plan with most flowers is to 

 cut off the floral envelopes and the stamens 

 near the base with a pair of small and sharp- 

 Fig. 95- Tomato- pointed scissors which cut well at the point. A 

 flower. I J Q Fi g 9Q snows t h e p O i n t a t which this cut 

 should be made in the fuchsia. With a little practice, one can 

 cut off the parts quickly. Fig. 96 shows a tomato-flower after 



