298 OBSERVATIONS ON THE NATURAL FAMILY
appearance, however, can hardly have escaped so accurate an observer; and his opinion respecting its cause may perhaps be inferred from an observation he has made on the stamina of the tribe in which it is most remarkable, namely Helianthea / whose filaments below the joint, he says, wither very soon after fcecundation. 1 To this wither- ing, which he does not mention as occurring in any other tribe, the phenomenon in question may be supposed to be ascribed.
But it appears to me, that the contraction or collapse of the filaments, from their previous state of extension, is a vital action, and not the effect of withering or decay, which, however, speedily follows it. For the contraction may in great part be prevented by the separation of the floret, when the filaments are in the state of extension : and in many genera of Compositae the antherae are never retracted, but continue to project till they fall off with the corolla.
This contraction is also analogous to the more evident motion or irritability of the filaments long ago noticed by Borelli and Alexander Camerarius 2 in CinarocejAalce ; and more fully described in the same tribe by Dal Covolo; 3 whose observations are confirmed and extended to other subdivisions of Compositae by Koelreuter. 4 A similar con- 120] traction and irritability of the style has been lately described by Mr. Ker in certain species of Arctotis}
The second species added to the genus by Willdeuow is Galea lobata, which Linnaeus, from the general appearance, I conclude, rather than from actual examination of the plant in Clifford's Herbarium, had referred to Conyza ; and having no specimen in his own Herbarium, the twofold error of supposing it to belong to Polygamia superflua, and to have a naked receptacle, remained uncorrected in all his subsequent works.
1 Journal de Physique, tome lxxviii, p. 278.
2 Ephemerid. Acad. Nat. Curios, cent, ix et x, p. 194.
3 Discorso della Irritabilita d 5 aicuni Fiori. Firenze, 1701.
1 Von Einigen das Geschleclit der Planzen betreffenden versuchen. 3. fortsetz. p. 1-25.
5 Botanical Register, i, 34.
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