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BULLETIN 289, U. S. DEPARTMENT OF AGRICULTURE. 



clover was in bloom very few nectar-producing plants were to be 

 found. Whether the honeybee would work on red clover to this 

 extent in a year of normal rainfall when the number of other nectar- 

 producing plants is larger is problematical, but our observations 

 and results show that the honeybee is able to spring the keels of red- 

 clover flowers and thereby cross-pollinate them. 



MECHANICAL CROSS-POLLINATORS OF RED CLOVER. 



A machine so constructed that a platform of brushes could be made 

 to strike clover heads with a vertical stroke was placed on the market 

 under the name of a clover cross-pollinizing machine (fig. 7). This 

 machine received some favorable comment. In view of this fact, 

 a number of experiments were outlined to test its efficiency and also 



Fig. 7. — Clover cross-pollinizi ig machine. 



to test the efficiency of different types of hand-operated brushes as 

 mechanical cross-pollinators of red clover. Some pints of red clover 

 were treated with various types of brushes at different times of day, 

 while other plats were treated when the clover heads were in different 

 stages of bloom. The direction of the strokes with the brushes was 

 also varied in order to see whether this would have any effect on 

 the yield of seed. 



MACHINE POLLINATION EXPERIMENTS. 



In order to determine the efficiency of a clover cross-pollenizing 

 machine several experiments were performed at Ames in 1911. 



Machines similar to the one used were offered for sale, on the market 

 at the time these experiments were being conducted. 



