326 Belling. 



This also shows a decrease of aborted ovules at the apex of the pod. 

 Hence, possibly, ovaries with genetically aborted embryo -sacs at the 

 apex of the pod are especially liable to drop as flowers.) 



About twenty flowers of the Velvet-China hybrid were back-crossed 

 with China pollen. They yielded 5 pods, on 4 different racemes. These 

 had 21 seeds and 10 aborted ovules, that is, 32 per cent of ovules 

 were aborted. In the distal halves of the pods the abortion of ovules 

 was 40 per cent. But 8 pods resulting: from flowers of the Velvet 

 bean crossed with China pollen gave only 7 per cent of aborted ovules. 

 Tliis shows that theie is no incompatiliility between the Velvet and 

 China; and that the pollen of the hybrid, although half abortive, is as 

 effective as that of the Cliina bean. 



To sum up: — Fifty per cent of the embryo -sacs of the Fi hy- 

 brids abort, long before maturity. The other 50 per cent are quite 

 normal. In other words, the functional megaspores segregate 

 into equal numbers of viable and nonrviable under the conditions 

 of their environment within the ovules. 



Fertility of the Second Generation. 



Pollen of the Second Generation. 



Velvet by Lyon. — The pollen was not examined in 1910. 



Lyon by Velvet. — The pollen of only a few plants was examined 

 in 1912, and no records were made. 



Velvet by Yokohama. — The pollen of these plants (480 seeds 

 were put in, 8 feet apart) was examined as they came into bloom, at 

 intervals from August to October, 1913. Two or more flowers from 

 different racemes were examined from each plant. If rain had entered 

 these flowers, more were examined. The October flowers were inde- 

 pendently examined tmce over. The following are the results: 



„ Plants with Plants with half _.., 



Date , ,, 41 ■ 11 u .• Differences 



normal pollen their pollen abortive 



August 7 . . . . 5() 23 —3:3 



August 2(1 ... . 40 40 — () 



September 8 . . . 4(5 «3 +17 



September 24 . . . 10 26 + 1<5 



October 13 ... . 22 43 +21 



Total plants I ho Iti.". + 1.") 



The interesting fact may be noticed that tlie plants with normal pollen 

 were, on the average, distinctly earlier in every stage of flowering. 



