NO. I IRRADIATED ASCARID OVA WRIGHT AND McALISTER II 



paper. Regardless of these negative results, it is apparent from our 

 tests that sunlight, through the ultraviolet spectrum at wave lengths 

 of approximately 3022 A, does exert a definite radiotoxic effect on 

 ascarid ova. However, owing to the relatively long exposures necessary 

 for the development of this lethal effect, it appears probable from a 

 practical standpoint that other factors, such as desiccation or high 

 temperatures, exert a more destructive action on these ova. In humid, 

 tropical climates, however, ultraviolet light probably does serve in 

 some measure in preventing the development of such ascarid ova as 

 are directly exposed to sunlight. 



SUMMARY AND CONCLUSIONS 



Irradiation of the ova of Toxocara caiiis and Toxascaris leonina at 

 measured wave lengths from a quartz monochromator and quartz 

 mercury arc resulted in a certain degree of radiotoxicity to the ova 

 exposed at certain wave lengths. 



A dosage of 684,000 ergs/cm' at wave lengths of 2652 and 2804 A 

 had a marked lethal effect on the ova of Toxascaris leonina but ap- 

 parently no effect on the ova of Toxocara canis. A similar dosage at 

 wave lengths of 2967, 3022, 3130, and 3650 A was without effect on 

 the ova of either species. 



A dosage of 27,400,000 ergs/cm' at a wave length of 3022 A re- 

 sulted in definite radiotoxicity on the ova of both species of ascarids. 

 Exposures to the same dosage at wave lengths of 3130 and 3650 A 

 showed no effect 



A dosage of 137,000.000 ergs/cnf at a wave length of 3022 A 

 showed a marked lethal effect on the ova of both species. In the case 

 of Toxocara, only 20.5 per cent of the irradiated ova developed to 

 embryonation as compared with 65.5 per cent embryonation in the 

 control culture; only 1.5 per cent of the Toxascaris ova reached 

 embryonation as against 42.0 per cent embryonation in the control 

 culture. The dosage employed was approximately equivalent to an 

 exposure of 60 hours noonday, midsummer sun at Washington, D. C, 

 or 12 days of average July sunlight. 



In all of these tests, the ova of Toxascaris leonina proved more 

 susceptible to the action of ultraviolet light than did the ova of Toxo- 

 cara canis. This difference is probably accounted for by the difference 

 in structure and pigmentation of the shell ; the mosaically patterned, 

 mammillated, darkly pigmented shell of Toxocara ova would appear to 

 disperse and to absorb more light than does the clear, unmammillated, 

 lightly pigmented shell of Toxascaris ova. 



