Apiary Experiments. 
9 
greater when the comb is more than an inch thick), then the thick¬ 
ening ot the cell wall by .01 of a millimeter increases the weight of 
comb one inch thick as much as thickening the midrib .10 of a 
millimeter. 
The thickness of the cell walls is much less than that of the 
midrib. In natural worker comb I have found it varying between 
.045 and .07 of a millimeter, with an average of not more than .06 
of a millimeter (.0024 of an inch). It has been thought by some 
that, though the bees may leave a heavy midrib in comb built on 
foundation, they will thin the cell walls down to the thickness in 
natural comb. 
Although the cell walls of a large number of sections of comb 
have been measured under the camera of a compound microscope, 
it is difficult to give these in tabulated form, as there is so much 
irregularity in thickness. The heaviest part, except the extreme 
outer end, is close to the base of the cell, and the thinnest is beyond 
the middle of its length. Where comb on heavy foundations was 
studied, the bases of the cells were found to have distinctly 
thickened walls for some distance out, and this thickening was often 
quite irregular, as may be seen at o in Figures g, h, and i of Plate 2, 
and Figure b of Plate 4. 
None of the foundations used in the experiment gave as deli¬ 
cately thin cell walls as are found in natural worker comb, except 
the thin and extra thin super foundations and, possibly, the rather 
shallow deep-cell foundation put out in 1899, which was placed 
upon the market by the A. I. Root Co., and which is being sold 
quite largely this year. I was not able in many cases to detect by 
measurements that the cell walls on these foundations exceeded the 
. average thickness in natural comb. The difference, if any, is very 
slight. Figure g in Plate 4 shows the thickness of the cell walls of 
this foundation in cross section, and at b of Plate 5 is shown a sec¬ 
tion of the walls parallel to the midrib and quite close to it. Figure 
a of Plate 5 is a section of fully drawn comb on this foundation, and 
it will be seen that the cell walls have nearly, or quite, the delicacy 
of those in natural comb. 
The “1898” deep-cell foundation with considerably longer cell 
walls, as shown at d of Plate 4, was not nearly so well worked ac¬ 
cording to my measurements. This may be due to the fact that 
the walls are so high that the bees cannot reach to the bottom with 
their mandibles to take hold of them and pinch them to the natural 
thinness They can only thin the lower portion of the walls by 
scraping them. As a rule, I have found the lower portion of the 
cell walls of comb on this foundation as thick as those built on the 
very heavy foundations, while in some cases they have been thinned 
very nearly to the delicacy of the walls in natural comb. A good 
illustration of the latter case is shown at the upper half of a of 
Plate 4, but even this sample compared with natural worker comb 
