42 APPLICATION OF PRINCIPLES TO FARM CROPS 



FIG. 33. Potato seed cases. New varieties of Irish potatoes are developed by plant- 

 ing the true seeds and then selecting the most desirable forms for propagation. See other 

 figures showing variation in seedling potatoes. (U. S. D. A.) 



FIQ. 34 



FIQ. 35. 



FIG. 34. Potato seedlings, of the short form desired for market; this would be the 

 form to propagate. It might have distinctive characters in texture, soundness, season, 

 etc., to entitle it to a new varietal name. (U. S. D. A.) 



FIG. 35. Potato seedlings, showing variations to the extremely long form. (U. S. D. A.) 



