270 AGRONOMY 



marks may be counted by fives. In the illustration which represents 

 the variation in the ray flowers of 55 specimens of sunflower the lowest 

 number of rays found was 12, and five speci- . _ 



mens possessed this number. The highest / \J 

 number was 20 with only one plant show- i i 



ing it. The average was 15, twelve heads ' ' 



possessing this number. The same data I O NJI 



can be expressed by a graph, similar to 



the one on page 52, in which the squares 13 //// / 

 may represent the number of parts in one 



direction and the number of specimens / J- //// /// 

 in the other. Express your work by both N 1 1 1^1 



methods. 15 IHJ IHJ II 



2. Visit any considerable area of one / hji i NJI 

 crop, wild or cultivated, and select the speci- 



mens you would breed from if you desired / 7 fiJJ II 

 to get () larger flowers, (i) more vigorous 



plants, (c) deeper color, (<Z) more abundant / Q IrU 

 fruit, or (e) broader leaves. 



3. Visit any patch of flowers in full / 7 // 

 bloom and search for variations in color, o/") / 

 size, and number of parts in the flower. i/ / 



4. In a row of young seedlings select FlG 195 variation in the 

 those that are (a) most vigorous, (I) weak- ray nowers O f sunflower 

 est, (c) deepest in color, (d) palest, (e) with 



broadest leaves, and (/) with narrowest leaves. Are the differences 

 great enough to be readily noticeable? Would they affect the crop? 



5. Visit and examine any sport that may be growing in the neigh- 

 borhood, especially the cutrleaved maple, Camperdown elm, weeping 

 mulberry, single-leaved mountain ash, single-leaved locust, nectarine, 

 purple-leaved plum, purple-leaved barberry, golden elder, yellow rasp- 

 berry, and the like. Compare with normal plants. 



6. In the school garden or other convenient place cross-pollinate 

 one or more flowers. Make a reciprocal cross in others. If two desirable 

 varieties are crossed, save the seeds for the next class to use. 



7. Plant hemp seed and study the difference between the male 

 (staminate) and the female (pistillate) plants. Examine cucumber or 

 melon plants and distinguish pistillate and staminate blossoms. 



8. If seeds of hybrid plants are to be obtained (perhaps left 

 by a previous class), grow the plants to observe the workings of 

 Mendel's law. 



