OF DIMOBPHTC AND TRTMORPHIC PLANTS, 395 



capsules were always selected for counting, in order to avoid over- 

 estimating the infertility of the several illegitimate plants. The 

 plants were generally allowed to be freely and legitimately fer- 

 tilized, through the agency of bees, by illegitimate plants belong- 

 ing to the two other forms growing close by. This is the fairest 

 plan, and was generally followed ; but in several cases (which will 

 always be stated) illegitimate plants were fertilized by pollen 

 taken from legitimate plants belonging to tlie other two forms ; 

 and this, as might have been expected, increased their fertility. 

 Unfortunately Lythrum Salicaria is much affected in its fertility 

 by the nature of the season ; and to avoid, as far as possible, error 

 from this source, my observations were extended over several 

 years. Some few experiments were tried in 18G3. The summer 

 of 1864 was too hot and dry, and, though the plants were 

 copiously watered, some few apparently suffered in their fertility, 

 whilst others were not in the least affected. The years 1865 and, 

 especially, 1866, were highly favourable. Only a few observations 

 were made during 1867. 



In order to judge of the degree of infertility of the various ille- 

 gitimate plants, the following statement of the average and maxi- 

 mum number of seeds produced by ordinary or legitimate plants, 

 when legitimately fertilized, some artificially and some naturally, 

 will serve as a standard of comparison, and may in each case be 

 referred to. But in order to save trouble, I have given under 

 each experiment the percentage of seeds to the nearest whole 

 number, as calculated in comparison with the standard number of 



the same form. 



Standards. 



Long -styled form ; average nuniber of seeds in each capsule 93; 

 'maximum numler ohserved in twenty-three capsules^ 159. 



Mid-styled form ; average number of seeds , ISO; maximum number 

 observed in thirty-one capsules^ 151. 



8ho7^t-styled form ; average nuniber of seeds, 83*5; hut we onay, 

 for the sake of brevity, say 83 ; maximum number observed in 

 ttoenty-fve capsules, 112. 



Class I. Illegitimate plants from the long-styled form^ fertilized 

 by pollen from the longer or shorter stamens of the same form. 



From this union I raised at different times three lots of seed- 

 lings, amounting altogether to 56 plants. I must premise that, 

 from not foreseeing the result, I did not keep a memorandum 

 whether the eight plants of the first lot were the product of the 



2d2 



