FUNCTION.] CATALEPSY. 155 



over the next flower below it, it will retain its new position 

 without springing back again to its original place ; and if it 

 is first bent to the right this will not prevent it being after- 

 wards bent to the left ; but it may be moved at pleasure to 

 one side or the other within the limits of half the circle 

 described by the points of the flowers round the axis on 

 which they grow. What is called catalepsy in this plant is 

 the power which the flowers possess of maintaining themselves 

 in a position artificially given to them, without their elasticity 

 bringing them back to the point from which they were 

 turned, as is the case in all other plants. 



This property is exceedingly striking when observed for 

 the first time, and converts the Physostegia, which has tall 

 erect stems, covered with long spikes of flowers, into a natural 

 vane, whose corollas indicate the direction of the wind with 

 great precision. 



This cataleptic property is only preserved by the flowers 

 when moved horizontally ; if raised up and down, they spring 

 back to their original position with considerable force. They 

 even oscillate, in recovering their place, with great rapidity, 

 which shows that their stalks are, at least in a vertical direction, 

 provided with a high degree of irritability. Similar results 

 are obtained from moving the flowers in all other directions 

 except the horizontal, to which the cataleptic effect is con- 

 fined. It is moreover exceedingly remarkable that the effect 

 should be limited to the period of flowering ; neither before 

 that time, when the flower-buds are pressed upon by their 

 bracts, nor afterwards when the pedicels are directed obliquely 

 upwards, is the phenomenon observable ; so that it appears 

 evident that this catalepsy is limited to the time of fertilisa- 

 tion ; it favours the projection of pollen upon the stigma by 

 the shocks communicated to the corolla by the wind, in 

 displacing it, and striking it against other flowers; and 

 M. Morren regards it as one of the numerous physiological 

 efforts which are manifested in such infinite variety at the 

 time of fertilisation. 



M. De Candolle, who has noticed this phenomenon, ascribes 

 it, with some doubt, to the " low degree of elasticity resident 

 in the flower-stalk/' (Physiologic Vegetale, i. 14); M. Morren's 



