SMITHSOXIAX MISCELLANEOUS COLLECTIONS 



VOL. 93 



The exposed area on each sHde was marked off with a diamond 

 point ; this area was equivalent to the dimensions of the Hglit ray dis- 

 charged from the aperture, or 5 by 30 mm. Eggs on the same sHde 

 outside of the irradiated area served as controls ; the control eggs were 

 therefore subjected to identically the same conditions during develop- 

 ment as were the irradiated eggs. After exposure, each slide was 

 immediately placed in a Petri dish and covered with a i per cent solution 

 of formalin, in which the eggs were permitted to develop. For the 

 most part the eggs adhered to the slide. The culture was allowed to 

 develop for a period of 8 to 9 days at temperatures ranging from 26° 

 to 28° C. At the end of this time, counts were made to determine the 



Table i. — Results of Exposure of Ova of Toxocara canis and Toxascaris leonina 



to Ultraviolet Light 



Series A — Exposed on May 23, 1934 

 Dosage — 684,000 ergs/cm^ 



percentage of embryonation in the eggs of the two species, both on the 

 control part of the slide and on the irradiated part of the slide. For each 

 count, 200 ova were taken. Table i summarizes the results obtained 

 from the irradiation of ova in series A. 



From an examination of the data it is apparent that the relatively 

 short exposure used in this series had little or no effect on the develop- 

 ment of the ova in the majority of cases. However, in two instances 

 the ultraviolet light appears to have exerted a definite toxic effect on the 

 ova of Toxascaris. On slide i ( wave length 2652 A) only 6.5 per cent 

 of the irradiated ova became embryonated, whereas 25 per cent of the 

 control ova became embryonated. On slide 2 (wave length 2804 A), 

 6 per cent of the irradiated ova were embryonated at the time the 

 count was made, whereas 29.5 per cent of the control ova were 



