1913] REED & COOLEY—TRANSPIRATION 423 
upon the apple varieties York Imperial and Ben Davis in orchards 
near Middletown, Virginia, in 1911 and 1912. All of the trees 
upon which studies were made were more than eight years old, 
and, aside from a certain amount of dwarfing due to continued 
attacks of cedar rust in one of the orchards, the trees were in good 
physiological condition. 
The time available for making satisfactory studies on transpira- 
tion of the diseased leaves was restricted to a period of about five 
weeks beginning near the middle of July. Before that date the 
cedar rust had not developed sufficiently to derange seriously, or 
at least uniformly, the activity of the apple leaves. Subsequent 
to this period, the fungus has injured or even killed more or less 
extensive areas in the infected leaves, and, in cases of severe infec- 
tion, the leaves begin falling during the latter part of August. 
The work here reported was carried out on leaves and twigs 
on the trees in their normal position. This method was believed 
to be preferable, since it has been shown by FREEMANS that actively 
transpiring shoots do not usually transpire at a normal rate when 
removed from their own roots. 
The data reported in the present paper were obtained by inclos- 
ing a few apple leaves in a glass cylinder and absorbing the exhaled 
water with weighed calcium chloride. The method of carrying 
on the experiments will be evident from the accompanying sketch 
of the apparatus (fig. 1), which is a type modified from that of 
FREEMAN (loc. cit.) and others. 
In its essentials the apparatus consisted of three parts: a wide 
mouth glass jar (A) which contained the twig under experimenta- 
tion, a calcium chloride tube (B), and an aspirator (C) which drew 
a known volume of air through the apparatus. The glass jar 
(A) was fitted with a soft rubber stopper which was cut through 
about three-fourths of its diameter. The opposing surfaces were 
notched at the center of the stopper to allow a twig to pass through, 
but the notch was small enough to insure a tight fit and prevent 
the passage of air. Two perforations in the stopper allowed glass 
tubes of 5 mm. diameter to pass. Tube 1, through which the air 
entered, extended to within 1 cm. of the bottom of the jar; tube 2, 
5 FREEMAN, G. F., A method for the quantitative determination of transpiration 
in plants. Bor. Gaz. 46:118. 1908. 
