150 
H. H. BARTLETT 
illegitimately raised plants have bad pollen grains, which is the usual 
symptom of sterility in hybrid plants. ..." This statement does 
not do justice to Darwin's evidence, which is quite convincing, es- 
pecially in the case Lythrum salicaria. This species is trimorphic, 
i. e., its flowers are long-styled, mid-styled or short-styled. Each 
flower type has two sets of stamens, coinciding in length with the 
styles of the two other types of flowers. Thus there are three kinds of 
stamens in the species and each bears pollen which is morphologically 
and physiologically different from that of the others. A pollination is 
legitimate when it takes place between a style and stamens of the 
same length. There are 1 8 possible combinations between the 3 forms, 
of which 6 are legitimate and 12 illegitimate. Darwin made all the 
difl^erent pollinations and found that only the legitimate ones were 
fully fertile. In regard to pollen sterility we will quote his own 
words. An illegitimate progeny from the long-styled form, pol- 
linated from the longer or shorter stamens of the same form, consisted 
of 56 plants, belonging to three lots. " In several plants of all three 
lots, many of the anthers were either shrivelled or contained brown 
and tough, or pulpy matter, without any good pollen grains, and they 
never shed their contents ; they were in the state designated by Gaertner 
as contabescent. ... In one flower all the anthers were contabescent 
excepting two, which appeared to the naked eye sound ; but under the 
microscope about two thirds of the pollen grains were seen to be small 
and shrivelled. In another plant, in which all the anthers appeared 
sound, many of the pollen-grains were shrivelled and of unequal sizes." 
An illegitimate progeny of nine plants resulted from the pollination of 
the short-styled form with pollen from the shorter stamens of the same 
form. "The anthers in many of the flowers on several plants were 
contabescent." Of 25 illegitimate plants from the mid-styled form, 
pollinated from the shorter stamens of the long-styled form, the pollen 
of 4 plants was examined "during the highly favorable season of 1866 
... ; in one mid-styled plant, some of the anthers of the longer sta- 
mens were contabescent, but in the other anthers the pollen grains 
were mostly sound, as they were in all the anthers of the shorter sta- 
mens; in two other mid-styled and in one long-styled plant many of 
the pollen grains were small and shrivelled ; and in the latter plant as 
many as a fifth or sixth appeared to be in this state." Darwin also 
expressly states that contabescent anthers occurred as a resu!" of il- 
legitimate pollination in Primula sinensis and Primula veris. 
