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 Helianihea ; whose filaments below the joint, he 

 says, wither very soon after foecundation.^ To this wither- 

 ing, which he does not mention as occurring in any other 

 tribe, the phsenomenon 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. Por 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 antherse 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^ in Cinarocephalae ; and 

 more fully described in the same tribe by Dal Covolo ;' 

 whose observations are confirmed and extended to other 

 subdivisions of CompositES by Koelreuter.* A similar con- 

 120] traction and irritability of the style has been lately 

 described by Mr. Ker in certain species of Arcfotis} 



The secotid species, added to the genus by Willdenow is 

 Calea 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. 



' Journal de Physique, tome Ixxviii, p. 278. 

 ^ Ephemerid. Acad. Nat. Curios, cent, ix et x, p. 194. 

 ^ Discorso della Irritabilita d' alcuni Fieri. Pirenze, 1764. 

 •* Von Einigen das Geschleoht der Planzen betreffenden versuolien. 3. fortsetz. 

 p. 125. 

 ■^ Botanical Register, i, 34. 



