[173]

Robinia

129-132

[174]

477 15

Chapter 7

three sets of seeds & grown in competition with one another. The intercrossed The plants from derived from intercrossing the self-fertilized now exceeded in height by a little, differently to what occurred in the experiment, in the last paragraphs the self-fertilized, viz as 100 to 92; and in fertility in a greater degree, viz as 100 to 73. I do not know whether this difference in the result corresponds compared with that in the previous & analogous case or may be attributed can be accounted for by the increased deterioration of the self-fertilised plants for from two additional generations of self-fertilisation and the consequent advantage of any cross even though whatever, although mainly between self-fertilised plants, subjected to nearly the same condition But however this maybe, the result from effects of crossing these self-fertilized plants of the eighth generation by with a fresh stock of were extremely striking; from for the plants seedlings thus raised was were to the self-fertilized of the ninth generation, as 100 to 52 in height, and as 100 to 3 in fertility! They were also to the intercrossed plants (derived from crossing two of the self-fertilised plants of the eighth self-fertilized generation) in height as 100 to 56, and in fertility as 100 to 4. Better evidence could not be derived desired of the potent influence of a cross by with a fresh stock on plants which had been self-fertilized from eight generations, and had been been cultivated all the time under nearly uniform conditions, in comparison with plants continuing continuously self-fertilized from for nine generations, or one intercrossed once intercrossed nearly in the