THE EFFECT OF ULTRAVIOLET RADIATION ON THE 



OVA OF THE ASCARID ROUNDWORMS TOXOCARA 



CANIS AND rOXASCARIS LEONINA 



By W. H. WRIGHT, 



Zoological Division, Bureau of Animal Industry, 



U. S. Department of Agriculture 



AND 



E. D. McALISTER, 



Division of Radiation and Organisms, 



Smithsonian Institution 



INTRODUCTION 



Through the courtesy of Dr. C. G. Abbot, Secretary of the Smith- 

 sonian Institution, the opportunity was presented to study the action of 

 ultraviolet light on the ova of the two species of ascarids commonly 

 infesting the dog. It was desired in the experiments reported here to 

 determine, if possible, the radiotoxic effect of ultraviolet light of 

 different wave lengths and, as a practical measure, to correlate the 

 possible sterilizing action of sunlight on the ova of these two species 

 of ascarids. 



The apparatus employed for the radiation of the ova, described in 

 detail by Brackett and McAlister (1932), consisted of a quartz mono- 

 chromator and a quartz mercury arc. This apparatus eliminates the 

 disturbing eft"ect of the large amount ol heat attending all total arc 

 exposures and permits irradiation by the different wave lengths of the 

 mercury spectrum. The intensities of the spectral lines employed were 

 as f ollow'S : 



2652 570 



In correlating the dosage employed with ultraviolet intensities in 

 sunlight, the determinations of Coblentz and Stair (1931) have been 

 used. These investigators gave the value of 65 microwatts per cm" 

 (650 ergs/sec. cm") for noonday, midsummer sun at Washington, 



Smithsonian Miscellaneous Collections, Vol. 93, No. 1 



