78 MIMULUS LUTEUS. CHAP. Ill 



Here the average height of the twenty-two crossed plants is 

 16-85, and that of the twenty-two self-fertilised plants 16 "07 ; or 

 as 100 to 95. But if four of the plants in Pot VII., which are 

 much shorter than any of the others, are struck out (and this 

 would be the fairest plan), the twenty-one crossed are to the 

 nineteen self-fertilised plants in height as 100 to 100 '6 that is, 

 are equal. All the plants, except the crowded ones in Pot VIII., 

 after being measured were cut down, and the eighteen crossed 

 plants weighed 10 oz., whilst the same number of self-fertilised 

 plants weighed lOi oz., or as 100 to 102 '5 ; but if the dwarfed 

 plants in Pot VII. had been excluded, the self-fertilised would 

 have exceeded the crossed in weight in a higher ratio. In all 

 the previous experiments in which seedlings were raised from a 

 cross between distinct plants, and were put into competition 

 with self-fertilised plants, the former generally flowered first ; 

 but in the present case, in seven out of the eight pots a 

 self-fertilised plant flowered before a crossed one on the 

 opposite side. Considering all the evidence with respect to 

 the plants in Table XXU., a cross between two flowers on the 

 same plant seems to give no advantage to the offspring thus 

 produced, the self-fertilised plants being in weight superior. But 

 this conclusion cannot be absolutely trusted, owing to the 

 measurements given in Table XXI., though, these latter, from 

 the cause already assigned, are very much less trustworthy than 

 the present ones. 



Summary of Observations on Mimulus luteus. In the 

 three first generations of crossed and self-fertilised 

 plants, the tallest plants alone on each side of the 

 several pots were measured ; and the average height 

 of the ten crossed to that of the ten self-fertilised 

 plants was as 100 to 64. The crossed were also much 

 more fertile than the self-fertilised, and so much 

 more vigorous that they exceeded them in height, even 

 when sown on the opposite side of the same pot after 

 an interval of four days. The same superiority was 

 likewise shown in a remarkable manner when both 

 kinds of seeds were sown on the opposite sides of a pot 

 with very poor earth full of the roots of another plant. 



