Development of Xerophthalmia in the Rat 81 



RAYED ANIMALS 







Init. weight 



Fin. weight 



Xerophthalmia 



Bat 



No. 



February 2 



June 17 



after 



27 



6 



3-3 grams 



72 



128 days 



28 



3 



29 grams 



70 



12 S days 



30 



a 



32 grams 



80 



31 



2 



40 grams 



88 





34 



9 



36 grams 



80 



140 days 



36 



$ 



59 grams 



110 



It can be seen from the table that there was no difference as 

 regard the rate of growth and incidence of xerophthalmia as the 

 result of treatment with ultra violet light. We could not tell 

 whether the earlier development of xerophthalmia in the males 

 is of any significance or only purely accidental. A 'histological 

 examination of the ribs of both series of rats was undertaken 

 with the view to detecting rickets. The results were negative. 



We are indebted to Dr. Hess for placing at our disposal the 

 sources of light mentioned. We also thank the pathological 

 department of the College of Physicians and Surgeons for help 

 extended to us. 



40 (2000) 



The influence of light and darkness upon the development of 

 xerophthalmia in the rat. 



Dy G. F. POWERS, E. A. PARK and NINA SIMMONDS. 



[From the Department of Pediatrics, Yale University School of 

 Medicine, New Haven, Connecticut, and the Department of 

 Chemical Hygiene, Johns Hopkins University, 

 Baltimore, Maryland.'] 



The preventive influence of direct sunlight and of radiation 

 with the mercury vapor quartz lamp upon the development of 

 experimental rickets in rats has been demonstrated in experi- 

 ments reported in previous studies. A logical further step was 

 to determine whether or not direct sunlight and radiation with 

 the mercury vapor quartz lamp would also prevent the develop- 

 ment of xerophthalmia in rats fed diets which, under ordinary 



