EYE, COMPOUND 
347 
wish a gasoline engine, prefer the older 
beveled-gear drive, with the ratio of 2 to 1 
—that is, one revolution of the crank shaft 
means two revolution of the reel carrying 
the comb. 
Many beekeepers having less than 100 
colonies use power outfits, but when there 
are more than 200 colonies to be extracted 
from, a gasoline engine and eight-frame ex¬ 
tractor will almost pay for themselves in 
one season. 
They do much quicker and more thoro 
work. It is impossible to extract all the 
honey by hand; and the result is, the 
combs go back to the hives very wet. Some 
of this honey will be saved by the beqs, 
but a large part of it is consumed and 
thereby as good as wasted. 
An important advantage of the larger 
extractors is their greater stability. With 
the two or even four frame size, it is nec¬ 
essary to put combs of equal weight oppo¬ 
site each other. Even then bracing must be 
done or else the can will tear itself loose 
from the floor. In case of the larger sizes, 
the difference in the weight of the combs 
does not throw the cans out of balance ap¬ 
preciably, hence no bracing or equalizing 
is necessary. 
EYE, COMPOUND. —An examination 
of the large compound eyes of a bee will 
show that the outside is made of hexa¬ 
gonal areas, thousands in number. Each 
of these hexagons is the outside of one of 
the elements of which the compound eye is 
composed; and, since they are all con¬ 
structed alike, a description of one will 
serve for all. Each of these elements is 
called an ommatidium. If, then, we take 
a section thru one of the compound eyes 
parallel with the top of the head of the 
bee, we shall get some of them cut length¬ 
wise, thereby showing best the structure, 
altho it is also necessary to cut other sec¬ 
tions at right angles to this plane in order 
to get the shape of some of the parts. The 
figures which accompany this show the om¬ 
matidium cut lengthwise. Another figure 
shows an ommatidium from the pupa state. 
The outside portion, already mentioned, 
is the lens layer l, and is composed of chit- 
in, as is all the rest of the outside covering 
of the bee. The section shows this cut 
open, so that only two sides of the hexagon 
are shown. 
c.c. 
o.-p.c. 
A.reU. 
I 
Fig. 1. 
bm. 
Fig. 1. — Ommatidium of adult 
eye of bee: 1, lens; c. c., crystal¬ 
line cone; o. p. c., outer pig¬ 
ment cells; c. p. c., corneal pig¬ 
ment cells, which, in the early 
stages, secrete the lens; r. h. b., 
rhabdome; ret, retinula; ret. 
n., nuclei of retinula cells; b. 
m., basement membrane. 
Fig. 2. —Ommatidium of pupa ; 
lettering as in Fig. 1; p. g. m., 
pigment forming in retinula. 
In Fig. 1 the pigment is not 
shown in the center portion of 
the retinula cells. 
