Plant Breeding. 277 



440. Cross-Fectindation is accomplished through 

 cross-pollination of the flowers (151) ; i. e., by placing 

 pollen from the anthers of a flower of one of the varie- 

 ties we desire to cross upon the stigma of the other 

 variety. 



441. Preparing the Flower for Crossing. To pre- 

 vent self-pollination (151) in perfect flowering plants 

 (153), we emasculate (e-mas'-cu-late) the flowers, i. e., 

 remove the anthers (143) before the pollen is mature. 

 Prior to maturity, the anthers 

 are generally pale in color and 

 nearly smooth on the 

 surface, with no visible 

 pollen, but a little later, 

 the pollen in most 

 plants is visible as a 

 bright yellow dust ad- ^ ,„ „ ^ . , 



° •' Fig. 171. Case o( instruments and 



hering to the anthers. ^'^^^^ ^°'^ crossing plants: 

 The anthers may be picked off with the forceps, or the 

 filaments that support them may be clipped off with the 

 points of the scissors. They must generally be removed 

 before the petals open (142). The latter may be gently 

 opened with the forceps or needle, or they may be care- 

 fully removed. 



In the flowers of certain plants, such as the pea, wheat 

 and grape, pollination takes place before the blossom 

 opens, hence in these plants it is necessary to emasculate 

 the flowers very early. 



442. To Prevent Undesired Pollination, the blossom 

 should be inclosed by tying over it a sack of thin cloth 

 or paper at the time of removing the anthers. The sack 



