78 ilK. BAEWiy OS THE EXISTENCE OF TWO TOHMS 



by insects. When insects are the agents of fertilization (and this 

 is incomparably the more frequent case both with plants having 

 separated sexes and with hermaphrodites), the wind plays no part, 

 but we see an endless number of adaptations to ensure the safe 

 transport of the pollen by the living workers. We can recognize 

 these adaptations most easily in iiTeguIar flowers ; but they do not 

 the less occur in perfectly regular flowers, of which those of Linum 

 offer an instance, as I will almost immediately endeavour to show. 



I have already alluded to the rotation of each separate stigma in 

 the long-styled form alone oi Linum perenne. In the other species 

 examined by me, and in both forms when the species are dimor- 

 phic, the stigmatic surfaces face the centre of the flower, and the 

 furrowed backs of the stigmas, to which the styles are attached, face 

 the circumference. This is the case, in the bud, with the stigmas of 

 the long-styled flowers of L. perenne. But by the time the flower 

 in this form has expanded, the five stigmas, by the torsion of that 

 part of the style which lies beneath the stigma, twist round and 

 face the circumference. I should state that the five stigmas do 

 not always perfectly turn round, two or three often facing only 

 obliquely towards the circumference. My observations were made 

 during October ; and it is not improbable that earlier in the season 

 the torsion would have been more perfect ; for after two or three 

 cold and wet days the movement was very incomplete. The flowers 

 etould be examined shortly after their expansion ; for their dura- 

 tion is brief, and, as soon as they begin to wither, the styles be- 

 come spirally twisted together, and the original position of the 

 parts is lost. 



He who will compare the structure of the whole flower in both 

 forms of L. perenne wiA. grandiflorum, and, I may add, of L.flavum, 

 will, I think, entertain no doubt about the meaning of this torsion 

 of the styles in the one form alone of L. perenne, as well as the 

 meaning of the divergence of the stigmas in the short-styled forms 

 of all three species. It is absolutely necessary, as we now know, 

 that insects should reciprocally carry pollen from the flowers of 

 the one form to those of the other. Insects are attracted by five 

 drops of nectar, secreted exteriorly at the base of the stamens, so 

 that to reach these drops they must insert their proboscides outside 

 the ring of broad filaments, between them and the petals. In the 

 short-styled form of the above three species, the stigmas face the 

 axis of the flower ; and had the styles retained their original up- 

 right and central position, not only would tlie stigmas have pre- 

 sented their backs to insects as they sucked the flowers, but they 



