IN SEVERAL SPECIES OF THE GENUS LINUM. 75 
apparently never penetrate the stigmatic tissue deeply, and the 
stigmas themselves do not become discoloured and twisted. 
This seems to me a remarkable physiological fact. The pollen- 
- grains of the two forms are undistinguishable under the micro- 
scope ; the stigmas differ only in length, degree of divergence, and 
in the size, shade of colour, and approximation of their papilla, these 
latter differences being variable and apparently simply due to the 
elongation of the stigma. Yet we plainly see that the two pollens 
and the two stigmas are widely dissimilar in action—the stigmas of 
each form being almost powerless on their own pollen, but causing, 
through some mysterious influence, 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 by some means mutually recognize each other. 
Taking fertility as the criterion of distinctness, it is no exaggera- 
tion to say that the pollen of the long-styled Linum grandiflorum 
(and conversely of the other form) has been differentiated, with 
respect to the stigmas of all the flowers of the same form, to a 
degree corresponding with that of distinct species of the same 
genus, or even of species of distinct genera. 
Linum perenne.—The dimorphism is here more conspicuous, and 
has been noticed by severalauthors. In the long-styled form the 
pistil is nearly twice as long as in short-styled ; in the latter the 
stigmas are smaller and, diverging more, pass out between the fila- 
ments of the stamens. I could detect no difference in the size of 
the stigmatic papilla ; in the long-styled form alone the stigmatic 
Surfaces turn round so as to face the cireumference of the flower: 
but to this point we shall presently return. Differently from what 
occurs in L, grandiflorum, the long-styled flowers have stamens 
hardly more than half the length of those of the short-styled. The 
size of the pollen-grains is rather variable ; after some doubt, Ihave 
come to the conclusion that there is no uniform difference between 
the pollen of the two forms. The long stamens in the short-styled 
form project to some height above the corolla, and, apparently from 
exposure to the light, the filaments are coloured blue. These longer 
stamens correspond in height with the lower part of the stigmas 
of the long-styled flowers; and the shorter stamens of the latter 
form correspond in the same manner in height with the shorter 
stigmas of the short-siyled flowers, 
I raised from seed twenty-six plants, which proved to be twelve 
long-styled and fourteen short-styled. They flowered well, but 
were not large plants, As I did not expect them to flower so 
G2 
