IMPROVEMENT OF THE POTATO. 393 



There is no constant difference due to selection of plants with 

 a single stem and those which branch just below and just above the 

 ground, providing they are equal in top weight and that it is cer- 

 tain that the branched selections are single plants. There appears, 

 however, to be an optimum shade of color in vines, constant with 

 the variety, which is correlative with, or a result of vigor in the 

 plant. Lighter colors gave fewer potatoes although these were of 

 good size, while darker colors either gave no set of tubers or a 

 large set of very small tubers. The latter condition sometimes 

 seems to be due to a very late setting of tubers in late varieties, 

 leaving too short a season for the tubers to mature. 



The actual crossing of the plants selected is a simple matter. 

 The corolla and stamens of the selected blossom of the mother 

 plant should be cut away before it is fully developed, and the blos- 

 som then bagged with a small waxed paper bag. When the stigma 

 is receptive (sticky), dust on the pollen collected from the "sire" 

 plant with a camel's hair brush. This pollination should be repeated 

 on two successive days, if the pistil has not fallen. It is better to 

 limit the fruits of the mother plant to two, but several flowers 

 should be pollinated in order to stimulate growth in the peduncle 

 of the cyme. When the fruit has begun to form, remove the bag 

 to allow free access to air and light. When the fruits are ripe, they 

 are gathered and allowed to dry. It is better for their viability to 

 squeeze out, clean and dry the seed, rather than allow them to stay 

 all winter in the berries where there is an opportunity for decay. 



FIG. 4. IRREGULAR CYME OF POTATO FLOWERS. ONE READY FOR POLLINATION. 



