FERTILIZATION IN THE VEGETABLE KINGDOM. 223 



unhealthy, and the experiment terminated without marked 

 result. Moreover, the remarkable vigor of growth in Hero 

 and its progeny was attended by somewhat increased fertil- 

 ity. Here, then, an idiosyncrasy arose from some utterly un- 

 known cause, — a spontaneous variation of constitution, which 

 was transmitted to posterity, and which gave all the benefit 

 of cross-fertilization, and somewhat more, both as to vigor 

 and fertility. A similar idiosyncrasy made its appearance in 

 the third generation of seedlings of Mimulus luteus. 



Discordant or anomalous facts like these seem confusing, 

 even though too few to affect seriously the grand result of 

 the numerous experiments ; but upon Darwinian principles, 

 in which adajstations are ultimate results, they are to be ex- 

 pected, as a consequence of the general and apparently vague 

 proclivity to vary. 



In Foxglove, — the flowers of which are naturally self -sterile 

 or nearly so, and in which crossing gave a marked advantage 

 over self-fertilizing, both as to growth and productiveness, — 

 a decided, though small advantage appeared to come from 

 the crossing of flowers on the same plant. 



In Origamim vulcjare., crosses were made between different 

 plants of a large clump, long cultivated in a kitchen-garden, 

 which had evidently spread from a single root by stolons, and 

 which had become in a good degree sterile, as is usual under 

 such conditions. The crossing caused rather more seed to 

 form ; but the seedlings from the crossed did not surpass in 

 growth those of the self -fertilized ; " a cross of this kind did 

 no more good than crossing two flowers on the same plant of 

 Ipomsea or Mimulus. Turned into the open ground, and both 

 self and cross-fertilized the following summer, and equal pairs 

 of the resulting seeds planted on opposite sides of two very 

 large pots, the crossed plants from seed showed a clear supe- 

 riority over their self-fertilized brethren, at the rate of 100 

 to 86. But this excess of height by no means gives a fair 

 idea of the vast superiority in vigor of the crossed over the 

 self-fertilized plants. The crossed flowered first and produced 

 thirty flower-stems, while the self-fertilized produced only 

 fifteen, or half the number. The pots were then bedded out, 



