450 BOTANICAL GAZETTE [JUNE 
from mathematically regular, hence any attempt at measuring 
the surface area will necessarily give only approximate results ; 
but let us assume for comparison that the difference between a 
galled and a healthy leaf on the one hand anda regularcone on the 
other is approximately equal. Ifwe multiply the diameter at the 
base by 7 = 3.14, thus getting the circumference ofa regular cone 
at the base, and this figure by one half the length of the needle 
(one half the height of a regular cone), we shall get the area of 
a regular cone. The calculated circumference is too large, for 
two of the lines bounding the base of a pine needle are straight; 
but, on the other hand, the diameter of a pine needle is less at 
the base than a short distance above. The cone, therefore, is not 
regular; the needle is larger above than at the base, tapering 
toward both base and tip. Nevertheless, using this faulty 
method of estimating surface areas, we have comparable figures 
—109.35%1™™ as the area of an average normal needle, and 
52.65°3™™ as the area of an average galled needle. The sur- 
face of average normal leaves, therefore, is approximately twice 
that of galled cones. 
The weight of the 20 normal leaves which I measured is 
0.85955" and of the 20 galled ones 0.395. So far as expenditure 
of leaf-building material is concerned, there is a difference of 
stomata should also be considered. The stomata appear alike 
on normal and on galled leaves, but there are four times as 
many on the former as on the latter. 
Between normal and galled leaves the physiological differ- 
ences will at least equal the anatomical ones. Thus there will be 
considerable differences in the amount of water lost through the 
stomata, in the amount of food made in the chlorophyll-con- 
taining tissues, and in the amount of food consumed in healthy 
and in diseased leaves. The larvae in the galls may consume more 
food than is made in the leaves at the bases of which they 
develop from the eggs, as they may be sufficiently nourished 
from the leaves alone. On this point there is at present no light. 
If the larvae consume more food than the immediately adjacent 
