44 



The Stomatograph. 



Cr. Contact closing relay circuit. (Dotted line represents position of same 



when relay circuit is open.) 

 R. Relay magnet. 



Ex. Rubber exit tube from gas-holder to nozzle p, passing through a condensed- 

 water trap-bulb. 

 G. Gasholder, with — 

 V, V. Inlet valve holes. 



L. Liquid (paraffin, water, or mercury) in which gas-holder floats. 

 Bp. Baffle plate at foot of gas-holder, carrying ring-weights. 

 C. Soft iron core. 

 S. Solenoid. 



Fig. 1b. — Plan of upper portion of pump to show arrangement of contact arm. Lettering 

 as in Fig. 1a. 



Fig. 2. — Semi-sectional view of chronograph. Drum represented by dotted lines. 

 P. Electro-magnetic marker, with pen. 

 r. Glass rod, bearing brass spiral. 

 sp. Brass wire spiral. 

 g, g. Driving rods, rotated by " L " pieces on hour spindle of clock. 

 CI. Clock. 



c. Upper detachable end of drum cylinder. 

 n. Lower ditto, with three-point nut. 



Fig. 3. — New pattern of porometer chamber, connected in use to nozzle p of pump. 



3a. Chamber made from cork and glass, with grooved flange containing paraffin wax, 

 as used in obtaining fig. 4. 



3b. Improved chamber, also with the waxed flange, but transparent at back. 

 Fig. 4. — Record for five consecutive days, converted to a curve, showing changes in 

 stomatal aperture as indicated by the variation in volume of air under constant 

 pressure which can be forced through the leaf-tissue. Plotted in terms of c.c. per 

 minute, through an area of leaf of 80 sq. mm., under a pressure of - 5 mm. of 

 mercury. Classified in 10-minute intervals. 

 Excepting on the first and fifth days the results represent the normal behaviour of the 

 Egyptian cotton plant (Gossypium peruvianum ?) under conditions which are nearly 

 identical with those of the field crop, excepting for some shading from direct sun in the 

 early morning and after 2.30 p.m., on account of adjacent trees and buildings. 



The leaf employed had just reached its full dimensions, on a plant with 10 leaves, 

 growing in the garden attached to the laboratory of the Khedivial Agricultural Society, 

 temporarily occupied by the Egyptian Government Department of Agriculture. 



