20 
change was made, In having assigned to them the s they bear, 
Mr. Nowack’s charts are presented in the light most favourable to him 
In each case where such a change has been mad ded both 
which it was finally relegated. How far the charts, even when arranged 
in this revised order, give the actual pressure changes over the area 
dates finally selected by Mr. Nowack when they passed into Mr. Scott’s 
hands, 
In view of the very great importance attached by Mr. Nowack to the 
curvatures and movements of the rac is, I have had the leaves on 
i oO h 
8 or 9 a.m. till late in the evening. Every day each healthy leaf on a 
plant performs considerable oscillations, and the record of these move- 
ments has been kept by a method similar in principle to that used by 
the Darwins and described in the first chapter of their “ Movements of 
front glasses of the case, so that two marks and the pulvinus of a leaf 
i mark on the front glass covering the 
Arranging the plants so that as many leaves as possible have their 
midribs approximately parallel to two of the four glass sides, their 
: d ep H . 
parallel glass faces. A line is then traced on the glass covering the mid- 
rib of each leaf; the eye of the observer being always so adjusted that 
the pulvinus of the leaf. in question is pierced by the imaginary line 
joining the two poiuts above mentioned, ; 
3y drawing such lines every few hours the vertical movements of 
the rachis are accurately recorded, and b i 
colours for successive days the movements 'over a considerable interval 
of time can be recorded on the same glass sheet without fear of con- 
fusion. When necessary these records can be traced off on to paper, 
and plotted out in a very simple manner into continuous curves, 
