17 
in certain ways. If a plant be darkened for some hours and then 
exposed to the light and darkened again, &c., this irregular position of 
_ the leaflets will be called forth ; the same thing will happen if th 
be inverted for a few hours. Unhealthy plants are more apt to show it 
than well-grown ones. 
On any leaf probably all the leaflets are not sensitive in absolutely 
the same "pl and sudden fluetuations in the conditions producing 
movements will make this want of equality apparent in the irregular 
position of the leaflets. pene en: 
transverse or saddle- bending of the ine . 
When this position was first shown on a leaf (end of August) Mr. No- 
wack rega t as indicative of electrieity. Since, however, he has 
observations are briefly stated. When the peculiar curvature in question 
ears on l 
They remained on these leaves till the middle of October, when the leaves 
were removed from the plant. The same occurred in other cases. I 
have found that this phenomenon is usually associated with a peculiar 
spotting or bleaching at the margin of each leaflet a ected near the 
apex. Whether this spotting is due to the puncture or bite of some 
insect, I cannot certainly say. However, my observations point to a 
connexion between the spotting and the curvature. The leav possessing 
a sweet taste, not unlike * liquorice-root,” they may not improbably be 
punctured by insects. 
11.—Movement of the Rachis ( Midrib). 
Previous to his sojourn in England Mr. Nowack would seem to have 
devoted little attention to the movements of the rachis of the leaf, 
except those extreme positions which he regards as indicating earth- 
quakes and seblagwetter. Recently, however, he has observed these 
imp in 
rtance . 
must be stated at the outset that these rachis-movements are entirely 
independent of the movements of the leaflets. At the time when 
mphlet was issued (1888) Mr. Nowack attached special importance 
only to certain extreme and well-marked rachis positions, in addition to 
(1. Cases in which the rachis is bent sharply down from the . 
pulvinus, making an angle of 45° or less with the stem. Such as these 
indieated by the extent to which the leaf apex is bent down; in the case 
of an itd for the immediate vicinity the leaf will be bent down, 
i rallel to the stem. 
becoming almost par , up ci Té wih 
'The forecast is only 
| or even week 1 
devise. A if I apprehend Mr. Nowack aright, the 
uld not be more than roughly indi- 
nce of the event co 
date of occurrence | views, and constructed a 
cated; later, however, he modified his former 
fresh hypothesis to be detailed below. 
U 60894. | B 
