1887. | BOTANICAL GAZETTE. 83 
as the sun is set; in fact the following of the sun is not so pronounced 
after 3 o’clock (and earlier on dark days) as up to that hour. It seems as. 
if the sun drew the leaf around.by its own attraction, and the blade moves 
back to its point of rest when the force is withdrawn. There was no evi- 
dent daily motion observed in the remaining portion of the long petioles. 
It is true that they varied their position from time to time, but with no: 
regularity. Petioles on the eastern side of a plant remain more nearly 
horizontal than those located elsewhere. Those upon the north and south 
sides are more upright, with a tendency to point eastward. The western 
leaves are nearly upright, so that the blades may be able to catch the di- 
rect rays of the morning sun. At night there is an evident falling of the 
petioles as if to assume a position of rest, while the blades become nearly 
horizontal at the same time. By 9, or at most 10 o’clock in the evening 
the plant reached its position of repose, and an hour or more before the 
sun’s morning rays can strike the plant the blades are all in position. 
Three distinct views of a malva patch may be obtained at any time when 
the sun is shining. If the view is, so to speak, from the-sun, that is, in the 
direction of the rays of light, only the upper surfaces of the leaves are 
seen ; if toward the direction of the sun, the under surfaces are in view. 
The difference between the shades of -greén of these two views is very 
marked. A third view is at right angles to the sun’s rays, from which 
point the leaves are only seen by their edges, which are inclined from 
the perpendicular, the angle depending upon the height of the sun at the 
time of observation. Upon a dark, stormy day the heliotropism of the 
leaves is in a large degree suspended.—Byron D. Ha.srep, Botanical 
Laboratory, Ames, Iowa. 
Leaf Prints.—Several years ago I devised a method of taking leaf 
prints of marked beauty, and a specimen of the work recently sent to Dr. 
Gray elicited the reply: “’Tis a new way; better send account of it to- 
BoranicaL Gazettes,” etc. I do so, prompted by the belief that the 
method may be of actual usefulness to the botanist as well as a refining 
recreation for those who love nature “on general principles.” There 
will be needed for the work: 1. A small ink roller, such as printers use 
for inking type. 2. A quantity of green printer’s ink. 3, A pane of 
stout window glass (the larger the better) fastened securely to an evenly 
planed board twice the size of the glass. A small quantity of the ink is 
put on the glass and spread with a knife, after which it is distributed 
evenly by going over in all directions with the ink roller. When this 
has been carefully done, the leaf to be copied is laid on a piece of waste 
Paper and inked by applying the roller once or twice with moderate 
Pressure. This leaves a film of ink on the veins and network of the leaf, 
and by placing it on a piece of blank paper and applying considerable 
Pressure for a few moments the work is done, and when the leaf is lifted 
