32 



quence of the want of diagrams and drawings to illustrate the 

 author's paper. 



The inflorescence of this plant is a close spike. The 

 flowers are opposite in pairs, in a decussate manner, and are 

 about three-quarters of the length of a calyx from each other. 

 The phsenomenon consists in this, that if you turn a flower 

 standing in face of you so far to the right or left as to stand 

 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 posi- 

 tion 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 direc- 

 tion, provided with a high degree of irritability. Similar 

 results are obtained from movinof the flowers in all other di- 

 rections except the horizontal, to which the cataleptic efffect 

 is confined. It is moreover exceedingly remarkable that the 

 effect should be limited to the period of flowering ; neither be- 

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

 bracts, nor afterwards when the pedicels are directed obliquely 

 upwards, is the pha^nomenon observable ; so that it appears 

 evident that this catalepsy is limited to the time of fertilization ; 

 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 



