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.
Eighth generation Table 2/9 : 8 : 113.25 : 8 : 96.65 : 85.
Ninth generation Table 2/10 : 14 : 81.39 : 14 : 64.07 : 79.
Tenth generation Table 2/11 : 5 : 93.70 : 5 : 50.40 : 54.
All ten generations together : 73 : 85.84 : 73 : 66.02 : 77.
(DIAGRAM 2/1. Diagram showing the mean heights of the crossed and self-fertilised plants of Ipomoea purpurea in the ten generations; the mean height of the crossed plants being taken as 100. On the right hand, the mean heights of the crossed and self-fertilised plants of all the generations taken together are shown (as eleven pairs of unequal vertical lines.))
The mean height of the self-fertilised plants in each of the ten generations is also shown in the diagram 2/1, that of the intercrossed plants being taken at 100, and on the right side we see the relative heights of the seventy-three intercrossed plants, and of the seventy-three self-fertilised plants. The difference in height between the crossed and self-fertilised plants will perhaps be best appreciated by an illustration: If all the men in a country were on an average 6 feet high, and there were some families which had been long and closely interbred, these would be almost dwarfs, their average height during ten generations being only 4 feet 8 1/4 inches.