frequency dependent on only one dimension, 
that of the radius; the other dimensions are 
not required to fit any half or whole wave 
configuration. In calculating the E,), mode, the 
resonant frequency and radius of the resonant 
cavity fit the formula whereA c = 2,613 a, 
Whenever we use this formula to calculate 
the resonant frequency for antennal sensilla, 
labial spines, or larval spines (fig. 5), we 
always end up in the IR region, invariably in 
the region of intermediate (IIR) orfarinfrared 
(FIR) between 1.54 and 18y%. These calcula- 
tions are used as an example and not as fact 
because exact configurations are not known. 
Measurements are at present being made with 
an electron microscope. The transfer of en- 
ergy from the spine transducers to the central 
nervous system would obviously involve no 
image conversion, but the signal could be 
used effectively in the same manner as a loop 
antenna in the radio frequencies, In such a 
system there would be either a null or a rein- 
forced signal strength, depending on the posi- 
tion of the paired antennae in relation to the 
signal. 






-6 
Water Vapor E - 300 - 10 
Transmission O 2.61- 2M 
Coeficient _ 300 - 407° 
5.22 =0.846( Good) Sto 2rAl 
= 57.4 Mega-mega 
cycles 
4 Microns(Hollow) 
72 Microns (Spine) 
Figure 5.--Typical measurements from insect spine and 
calculations of E, mode, Transmission efficiency of 
this calculated frequency depends on water vapor 
transmission coefficient at resonant frequency. 
161 
With regard toimage conversion, the obvious 
area of interest is the compound eye. Callahan 
(1965c) showed that visible, and especially 
shortwave, ultraviolet light quickly day-con- 
ditions the eye of the corn earworm moth 
(Heliothis zea (Boddie)), The eye of this moth 
is ideally suited for experiments, because the 
change from a daylight-adapted green to a 
totally dark-adapted black can be followed 
throughout its transformation. At full moon, 
for instance, the eye is neither green nor 
totally black with the central mirrorlike glow, 
but is instead an in-between murky, brownish 
color. 
Callahan (1965c) postulated that the night- 
adapted eye becomes an IR optic-electro- 
magnetic radiometer, since the corneal lens 
appears to function as an achromatic doublet 
and the crystalline cone as a quarter-wave, 
dielectric, coated field lens. During dark 
adaptation, the crystalline cone is coated with 
a pigment that in thickness is a quarter-wave 
of its diameter. The tracheal tapetum may well 
be an IR-collecting mirror. 
Mazokhin-Porshnyakov (1963) showed that 
certain night-flying moths are color blind 
under very low light intensities, but have 
color perception at high crepuscular inten- 
sities. The electroretinogram (ERG) of day-~ 
adapted moths under relatively strong light 
(several tens of luxes) was extremely small 
in contrast to that under low light conditions. 
He obtained responses of 25yuv. from a dark 
midnight sky, with the ERG reaching 10-15 
mv. when illumination was in the order of 
15 lux from an electric bulb. Mazokhin-Por- 
shnyakov interpreted his data in terms of 
reflected illumination from the night sky. 
This, I believe, was a misinterpretation of 
the data insofar as visible light was concerned. 
I believe that this work reinforces my hy- 
pothesis that the night-adapted eye is an IR 
detector. It seems to me that the insect eye is 
dependent on the type of radiation it receives 
from incandescent point sources of light, and 
that its wavelength sensitivity is entirely a 
relative phenomenon dependent on incandes- 
cence in nature, whether or not the incandes- 
cence is from the sun at daylight, or a corn 
plant, or another moth at night. Thus, the 
sensitivity of the insect eye could be compared 
to an incandescent lamp and rheostat (fig. 2), 
