390 BOTANICAL GAZETTE [NOVEMBER 
To determine whether the free access of air is prevented by corks 
or disks such as were used in Detmer’s experiment, it is sufficient to 
close the stomata in a similar manner and still admit light. This was 
done by pinning only a narrow ring of cork, in place of the whole 
disk, on the upper surface of the Primula leaf, exactly opposite the 
disk on the lower surface. By this device light is admitted and the 
external approach to the stomata is obstructed. 
The veins of the primula leaf, especially near the petiole, are much 
more prominent than those of tropaeolum, so the position of the 
Fic, 2 gas! a same; a, area 
‘ covered b isk on lower sur- 
Fic. 1.—Leaf of Primula ob- face and enclosed by cork ring 
conica,;, a, a, folds which admitted on upper; 4, after forty minutes 
CO,; 4, space enclosed by cork. exposure uncovered 
cork must be near the margin of the leaf to make the experiment 
differ as little as may be from the original. In the first experiments 
the upper cork was placed over the larger veins, leaving some space 
for the circulation of air and asa result starch was deposited along 
these veins (fig. 7). 
Still attached to ne plant and with the corks adjusted, the upper 
one being only a ring, as described above, another leaf was placed in 
diffuse light two days, then in direct sunlight forty minutes. After 
removing the cork half of the leaf was cut off, the cut passing through 
the covered part (fg. 2); the half remaining on the plant was left in 
the sun forty minutes longer. In the part first removed there was no 
starch in the portion enclosed by the ring of cork (a, fig. 2), while in 
the second half, which was left without corks in the light forty minutes 
longer, there was considerable starch in the corresponding area. 
