A preliminary survey of the effects of ultra violet light on normal rabbits.

With no prejudice regarding the results to be obtained we have exposed five series of normal rabbits to the quartz mercury arc lamp daily for periods of three to seven weeks and observed at autopsy the weights of certain endocrine glands in relation to the body weights of the animals. It was expected that this survey might orient us for further studies in the biophysics of ultra violet light. The survey was made possible by the cordial cooperation of Doctors Brown, Pearce, and Van Allen, who placed at our disposal unpublished figures from similar examinations on a large number of normal rabbits covering a period of two years. Many controls are required because of individual and especially seasonal variations in the gland/body weight ratio.

Light colored or albino male rabbits, with ears shaved and backs clipped, in groups of eight (two controls), were exposed to the unfiltered radiations of a quartz mercury arc lamp for 30 minutes daily at a distance of one meter. This arbitrary dosage was probably too large at first and relatively ineffective during the final periods, when pigmentation had occurred. It caused a marked erythema with some desquamation, followed by moderate pigmentation. At the expiration of the chosen periods the rabbits were etherized and bled from the aorta. The following glands were weighed and examined in gross and microscopically: pineal, hypophysis, external parathyroids, thyroid, thymus, adrenals, and testicles. The weights of these glands were recorded in milligrams per kilogram net body weight after removel of the gastro-intestinal tract and its contained food and feces, and the expression of bladder urine.

The changes in weight, per cent, compared with the figures for 15 to 36 normal control rabbits examined at the same season of the year are shown in the accompanying table.