152 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



When pollination is effected between two beets, although of 

 the same progeny, the percentage of fertilization appears to be 

 limited only by the refinement of the technic. These results are 

 tabulated above. 



Xo microscopic examination has yet been made to ascertain the 

 behavior of the pollen tubes under the various conditions men- 

 tioned. Xo explanation or hypothesis is ventured at this time 

 to account for the different responses observed on an individual 

 beet. It is probable that minute biochemical differences exist, 

 which increase in magnitude as the physical intimacy or relation- 

 ship decreases. Other experiments have shown that the various 

 buds on the crown of a seed beet behave as separate individuals, 

 and that each bud on one beet may assume a different morpho- 

 logical development from the others in response to modifications 

 in environmental factors. 



Explanation of plate 20 



A plat of seed beets in full bloom at the experiment station, Ogden, Utah, showing 

 isolation tents of various sizes. It was found that wind-borne pollen can sift through 

 these tents and cross-pollinate the protected seed beets. 



