38 POTATO DEVELOPMENT WORK IN WISCONSIN. 



crop of such, large magnitude and of such commercial impor- 

 tance as is the potato crop is well worthy of much attention. Be- 

 fore taking up the question of seed selection I wish to invite your 

 attention by means of lantern slides to some of the work that is 

 being done by the U. S. Department of Agriculture in an effort 

 to develop improved varieties of potatoes through the growing of 

 large numbers of seedlings. The picture which you now see upon 

 the screen is of two Avell developed potato blossoms one of which 

 has had its anthers removed, the flower so treated is said to be 

 emasculated. The next two pictures represent a cyme of potato 

 flowers before and after emasculation. The flower should be em- 

 asculated before the petals unfold. The application of pollen to 

 the stigma of the flower is a comparatively simple process the pic- 

 ture at which you are now looking shows the method employed by 

 the speaker. The corolla of the flower used for the pollen par- 

 ent is pushed back and the anther held over the end of the 

 thumb nail; in this position, the pollen is easily jarred out upon 

 the nail whence it is readily transferred to the stigma of the 

 pistil to be fertilized. When the cross has proved successful 

 the seedballs swell very rapidly. I have seen almost fully de- 

 veloped berries seven days after the pollen was applied. 



The cross sectioned berries at which you are now looking shows 

 the position of the seeds in the seedball. A well developed seed- 

 ball may contain three hundred or more seeds but where the 

 varieties crossed are not physiologically similar there may not be 

 over twenty-five seeds. The seeds are most easily removed from 

 the berries by crushing them into a pulp and throwing them into 

 a vessel of water, in a few days sufficient fermentation will have 

 developed to disintegrate the pulpy mass and release the seeds. 



The difference in specific gravity of the seeds and pulp allows 

 the former to settle to the bottom of the vessel while the pulp 

 rises to the top. By pouring water into the vessel the pulp can 

 be floated off and the seeds recovered. After drying, the seeds 

 can be stored until wanted for sowing. 



When planted in a loose friable soil and placed in a room tem- 

 perature to say 30 F. at night the seeds germinate in from nine 

 to fourteen days. The seedlings on the screen arc six weeks old 

 from the time of sowing the seed. We have frequently had them 

 much larger in the same length of time. The grower of potato 

 seedlings has many surprises in store for him owing to the infin- 

 ite number of variations that occur. Some seedlings like the one 



