PLATE I. 



Figs. 1 and 2. — The upper portions of the same two main stems of a growing tobacco 

 plant. 



The photograph for fig. 1 was taken 3 p.m., June 21, 1900, immediately after the 

 numbered flowers had been emasculated and pollinated, and the lettered flowers had 

 been emasculated but not pollinated. 



The photograph for fig. 2 was taken 3 p. m., June 23, or just forty -eight hours 

 later than that for fig. 1, and shows that premature pollination has caused flowers 1, 

 2, and 6 to fall, while the more mature flowers, 3, 4, and 5, show no injury from 

 pollination, but, on the contrary, were fecundated and set seed pods, as shown in 

 PI. II, fig. 1. 



Flowers 1 and 2, fig. 1, would not have been receptive for two days and flower 6 

 for three days, and according to results of experiments they were expected to fall 

 about thirty-six hours after pollination. 



Flowers 3, 4, and 5 would have been fully open and receptive in one day and were 

 expected to give a fair percentage of seed pods. 



If early emasculation had caused the falling, flowers r and d should have fallen 

 also. 



The advancement of an unmolested flower may be studied by observing the small 

 bud on the right in fig. 1 and its growth as shown by fig. 2 and the forming seed pod 

 in PI. II, fig. 1. 



42 



