302 REPRODUCTION 



insects and prevent wind-pollination : allow the stigma to mature, 

 which usually takes two or three days according to the age of 

 the flower when emasculated. 



(iii) When the stigma is ready, remove some ripe stamens 

 from the flowers of the plant to be used as the male parent of 

 the cross, and after lightly crushing the anther on the finger- 

 nail so as to set free the pollen, transfer the latter by means of 

 forceps to the stigma. To ensure absolute accuracy the flowers 

 from which the pollen is taken should have been previously 

 enclosed in a paper bag and allowed to open there : if this 

 precaution is neglected and stamens are merely taken casually 

 from open flowers on the male parent there is no certainty about 

 the cross for foreign pollen may have been brought into contact 

 with them by the wind or by insects. 



(iv) After pollination has been effected the flower must be 

 again enclosed in a paper bag and kept there until the seeds 

 have been fertilised and the fruit has begun to grow. 



The bag may then be removed and the fruit and seeds allowed 

 to ripen in the ordinary way ; in the case of fruits, such as apple, 

 pear and raspberry, it is necessary to protect the ripening fruit by 

 means of a muslin bag or coarse net. 



