any great difference when only the plants under 36 inches in height were excluded.  Nor again when all the plants, however much dwarfed and unhealthy, were included.  In this latter case the Colchester-crossed gave the lowest average of all; and if these plants had been in any marked manner superior to the other two lots, as from my former experience I fully expected they would have been, I cannot but think that some vestige of such superiority would have been evident, notwithstanding the very unhealthy condition of most of the plants.  No advantage, as far as we can judge, was derived from intercrossing two of the grandchildren of Hero, any more than when two of the children were crossed.  It appears therefore that Hero and its descendants have varied from the common type, not only in acquiring great power of growth, and increased fertility when subjected to self-fertilisation, but in not profiting from a cross with a distinct stock; and this latter fact, if trustworthy, is a unique case, as far as I have observed in all my experiments.]

Summary on the growth, vigour, and fertility of the successive generations of the crossed and self-fertilised plants of Ipomoea purpurea, together with some miscellaneous observations.

In Table 2/17, we see the average or mean heights of the ten successive generations of the intercrossed and self-fertilised plants, grown in competition with each other; and in the right hand column we have the ratios of the one to the other, the height of the intercrossed plants being taken at 100.  In the bottom line the mean height of the seventy-three intercrossed plants is shown to be 85.84 inches, and that of the seventy-three self-fertilised plants 66.02 inches, or as 100 to 77.

Table 2/17.  Ipomoea purpurea.  Summary of measurements of the ten generations.

Heights of Plants in inches: 

Column 1:  Name of Generation.

Column 2:  Number of Crossed Plants.

Column 3:  Average Height of Crossed Plants.

Column 4:  Number of Self-fertilised Plants.

Column 5:  Average Height of Self-fertilised Plants.

Column 6:  n in Ratio between Average Heights of Crossed and
Self-fertilised Plants, expressed as 100 to n.

First generation Table 2/1 :  6 :  86.00 :  6 :  65.66 :  76.

Second generation Table 2/2 :  6 :  84.16 :  6 :  66.33 :  79.

Third generation Table 2/3 :  6 :  77.41 :  6 :  52.83 :  68.

Fourth generation Table 2/5 :  7 :  69.78 :  7 :  60.14 :  86.

Fifth generation Table 2/6 :  6 :  82.54 :  6 :  62.33 :  75.

Sixth generation Table 2/7 :  6 :  87.50 :  6 :  63.16 :  72.

Seventh generation Table 2/8 :  9 :  83.94 :  9 :  68.25 :  81.