Infrared Loss Theory of Olfaction Untenable

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Abstract
Osmic radiation receivers descr. by Miles and Beck to determine quantitative reactions of honeybees in outdoor expts. were refined by maintaining the temp. of the enclosed odorants at 2oC. less than the room temp. A pair of osmic radiation receivers were incorporated in an air-tight apparatus which held constant the air purity, humidity, illumination, and rate of air flow. Responses of blowflies to 4 attractive odorants within the receivers, and of honeybees to clover honey, were counted during observation intervals of a fraction of a sec. or 5 min. Most expts. were carried on for 1 hr., a few for 2-3 hrs., and the sample size averaged 49.7 insects/test. 3 series of expts. with blowflies and honeybees produced a negative result. Small numbers touched the physiological contact surfaces and differences between controls and exptl. stimuli were not significant, the means for the controls of several tests exceeding the alleged exptl. stimulus. A 4th series with honeybees utilized supplementary baits outside the osmic radiation receivers, similar to the setup descr. by Miles and Beck. Aqueous honey soln. yielded a significantly larger mean number of contacts with the exptl. crystal than the control, while dilute sucrose soln. did not. The only positive result, however, may not be accepted as evidence for an infrared loss mechanism of olfactory reception because the bees very probably tracked small quantities of the supplementary honey soln. onto the vertical faces of the crystals. Thus, this chemical attractant makes it impossible to identify the principal olfactory stimulus as a physical factor. Inasmuch as a larger percentage of contacts with the exptl. crystals was instantaneous to brief in all tests, and the insects did not swarm upon the alleged source of the stimulus in large numbers, it was concluded that chance was the cause of most contacts with exptl. and control crystals while the insects made routine examinations of the inside of the testing apparatus. Miles and Beck''s results of field expts. are open to serious doubt because of the possible contamination of their thallium bromoiodide crystals, and on the basis of results of the unbaited series of expts. with captive insects.

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