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 phenomenon 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 moving the flowers in all other di- 
rections except the horizontal, to which the cataleptic effect 
1s 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 phenomenon observable; so that it appears 
evident that this catalepsy is limited to the time of fertilization ; 
1t 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 
