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Show 90 HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. stigmatic tissue deeply, and the stig~as themselves do not soon become discoloured and twisted. This seems to me a remarkable physiological fact. The pollen-grains of the two fonn~ are un~istinguis~lable under the microscope; the stigmas differ only In length, degree of divergence, an~ in t~e size, shade of colour, and approximation of theu papillre, these latter differences beino- variable and apparently due rnerely to the degree ;f elongation of the stigma. Yet we plainly see that the two kinds of P?llen and the ~wo stigmas are widely dissimilar i?- then mutual reaction -the stiamas of eaeh form being almost powerless on 0 their own pollen, but causing, through some myste-rious influence, apparently by simple contact (for I could detect no viscid secretion), the pollen-grains of the opposite form to protrude their tubes. It may be said that the two pollens and the two stigmas mutually recognise -each other by some means. Taking fe~tility as the criterion of distinctness, it is no exaggeration to say that the pollen of the long-styled Linum g14 andijlorum (and conversely that of the other form) has been brought to a degree of differentiation, with respect to its action on the stigma of the same form, corresponding with that existing between the pollen and stigma of species belonging to distinct genera. Lin'wn perenne.-rrhis species is conspicuous! y heterostyled, as has been noticed by several authors. The pistil in the long-sty led form is nearly twice as long as that of the short-styled. In the latter the stigmas are smaller and, diverging to a greater degree, pass out low down between the filaments. I could detect no difference in the two forms in the size of the stigmatic papillre. In the long-styled form alone the stigmatic surfaces of the mature pistils twist round, so as to face the circumference of the flower; but to this point I CHAP. III. LINUM PERENNE. 91 shall presently return. Differently from what occurs in L. grandiflorum, the long-sty led flowers have stamens hardly more than half the length of those in the shortstyled. The size of the pollen-grains is rather variable; after some doubt, I have come to the conclusion that there is no uniform difference between the grains in the two forms. The long stamens in the short-sty led form project to some height above the corolla, and their £.la1nents are coloure<l blue apparently from exposure to the light. The anthers of the longer stamens correspond in height with the lower part of the stigmas of the long-styled flowers; and the anthers of the shorter stamens of the latter correspond in the same manner in height with the stigmas of the short-styled flowers. I raised from seed twenty-six plants, of which twelve proved to be long-sty led and fourteen short-sty led. They flowered well, but were not large plants. As I did not expect them to flower so soon, I did not transplant them, and they unfortunately grew with their branches closely interlocked. All the plants were covered under the same net, excepting one of each form. Of the flowers on the long-styled plants, twelve were illegitimately fertilised with their own-form pollen, taken in every case from a separate plant; and not one set a seed-capsule: twelve other flowers were legitimately fertilised with pollen from short-styled flowers; and they set nine capsules, each incl ucling on an average 7 good seeds, ten being the maximum number ever produced. Of the flowers on the short-styled plants, twelve were illegitimately fertilised with ownform pollen, and they yielded one capsule, including only 3 good seeds; twelve other flowers were legitimately fertilised with pollen from long-styled flowers, and these produced nine capsules, but one was bad |