Fig. U. — (Upper photograph.) Ophthalmia in dog as the result of diet deticient 

 in vitamin A. (Steenbock, Nelson and Hart, 1921.) 



Fig. 12. — (Lower photograph.) Same dog shown in Fig. 11 cured in 10 days 

 by addition to his diet of 20 cubic centimeters cod-liver oil per day. (Steenbock, 

 Nelson and Hart, 1921.) (By permission of the American Journal of Physiology.) 



