HYBRIDIZATION 345 
wooden label with copper wires which is attached to the ear. If it is de- 
sired to make a second pollination the bag containing pollen may be tied to 
the plant alongside the ear and the same process repeated one or two 
days later. By close observation of the developing stigmas and pollinat- 
ing at the most propitious time well developed ears can be secured from 
a single pollination. Fig. 142 illustrates the principal features above 
described. : 
Fic. 142.—Hybridization of maize. Right, plant just previous to anthesis with leaves 
subtending ears stripped off; left, the same plant with bag enclosing tassel and cylinders 
covering ears. 
Method of Hybridizing Wheat.—This plant has numerous hermaph- 
rodite flowers arranged in a branched spike (Fig. 148, upper left). Each 
spikelet bears two rows of bracts or glumes (Fig. 148, 2). The lowest 
two bracts are sterile but each of the next four usually subtends a flower 
while at the top of the spikelet are two or three rudimentary flowers. 
Each flower consists of an ovary with two much branched stigmas (Fig. 
143, 12, 13) and three stamens which are shown in cross-section in Fig. 
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