In Pot 4, in which the plants were extremely crowded, the two lots were at first equal; and ultimately the tallest crossed plant exceeded by a trifle the tallest self-fertilised plant.  This recalled to my mind an analogous case in the one generation of Petunia, in which the self-fertilised plants were throughout their growth taller than the crossed in all the pots except in the crowded one.  Accordingly another trial was made, and some of the same crossed and self-fertilised seeds of tobacco were sown thickly on opposite sides of two additional pots; the plants being left to grow up much crowded.  When they were between 13 and 14 inches in height there was no difference between the two sides, nor was there any marked difference when the plants had grown as tall as they could; for in one pot the tallest crossed plant was 26 1/2 inches in height, and exceeded by 2 inches the tallest self-fertilised plant, whilst in the other pot, the tallest crossed plant was shorter by 3 1/2 inches than the tallest self-fertilised plant, which was 22 inches in height.

Table 6/84.  Nicotiana tabacum (first generation).

Heights of plants measured in inches.

Column 1:  Number (Name) of Pot.

Column 2:  Crossed Plants, May 20, 1868.

Column 3:  self-fertilised Plants, May 20, 1868.

Column 4:  Crossed Plants, December 6, 1868.

Column 5:  self-fertilised Plants, December 6, 1868.

Pot 1 :  15 4/8 :  26 :  40 :  44.

Pot 2 :  3 :  15 :  6 4/8 :  43.

Pot 3 :  8 :  13 4/8 :  16 :  33.

Pot 4 :  5 :  5 :  11 4/8 :  11.

Total :  31.5 :  59.5 :  74.0 :  131.0.

As the plants did not grow to their proper height in the above small pots in Table 6/84, four crossed and four self-fertilised plants were raised from the same seed, and were planted in pairs on the opposite sides of four very large pots containing rich soil; so that they were not exposed to at all severe mutual competition.  When these plants were in flower I neglected to measure them, but record in my notes that all four self-fertilised plants exceeded in height the four crossed plants by 2 or 3 inches.  We have seen that the flowers on the original or parent-plants which were crossed with pollen from a distinct plant yielded much fewer seeds than those fertilised with their own pollen; and the trial just given, as well as that in Table 6/84, show us clearly that the plants raised from the crossed seeds were inferior in height to those from the self-fertilised seeds; but only when not greatly crowded.  When crowded and thus subjected to very severe competition, the crossed and self-fertilised plants were nearly equal in height.

Crossed and self-fertilised plants of the second generation.