66 MIMULUS LUTEUS. Chap. IIL 



fertilised ones on the opposite side of the same pot, though not 

 nearly to so great a degree as before, when they were subjected 

 to very severe competition. 



Crossed and self-fertilised Plants of the Third Generation. 

 Crossed seeds from the crossed plants, and self-fertilised seeds 

 from the self-fertilised plants of the last generation, were sown 

 thickly on opposite sides of a small pot, No. I. The two tallest 

 plants on each side were measured after they had flowered, and 

 the two crossed ones were 12 and 7 5 inches, and the two self- 

 fertilised ones 8 and 5- inches in height ; that is, in the ratio of 

 100 to 69. Twenty flowers on the crossed plants were again 

 crossed and produced twenty capsules ; ten of which contained 

 1 33 grain weight of seeds. Thirty flowers on the self-fertilised 

 plants were again self-fertilised and produced twenty-six 

 capsules ; ten of the best of which (many being very poor) con- 

 tained only -87 grain weight of seeds; that is, in the ratio of 

 100 to 65 by weight. 



The superiority of the crossed over the self-fertilised plants 

 was proved in various ways. Self-fertilised seeds were sown on 

 one side of a pot, and two days afterwards crossed seeds on the 

 opposite side. The two lots of seedlings were equal until they 

 were above half an inch high ; but when fully grown the two 

 tallest crossed plants attained a height of 12s and 81 inches, 

 whilst the two. tallest self-fertilised plants were only 8 and 5| 

 inches high. 



In a third pot, crossed seeds were sown four days after the 

 self-fertilised, and the seedlings from the latter had at first, as 

 might have been expected, an advantage; but when the two 

 lots were between 5 and 6 inches in height, they were equal, 

 and ultimately the three tallest crossed plants were 11, 10, and 

 8 inches, whilst the three tallest self-fertib'sed were 12, 8s, and 

 7i inches in height. So that there was not much difference 

 between them, the crossed plants having an average advantage 

 of only the third of an inch. The plants were cut down, and 

 without being disturbed were transplanted into a larger pot. 

 Thus the two lots started fair in the following spring, and now 

 the crossed plants showed their inherent superiority, for the two 

 tallest were 13 inches, whilst the two tallest self-fertilised plants 

 were only 11 and 8i- inches in height ; or as 100 to 75. The 

 two lots were allowed to fertilise themselves spontaneously : the 

 crossed plants produced a large number of capsules, whilst the 

 nelf-fertilised produced very few and poor ones. The seeds 



