278 THE VITAMINS 



a deficient diet. The xerophthalmia observed among these Danish chil- 

 dren was regarded as one phase of their condition of malnutrition. 

 The eye disease appears to have been quite definitely related to de- 

 ficiency of vitamin A in the diet since it was cured by feeding with 

 whole milk or with cod-liver oil and in 1918 the disease nearly disap- 

 peared from the community coincidently with the general introduction 

 of butter into the dietary of the poorer people, this being brought about 

 through government food regulations. Seasonal variation of the inci- 

 dence of the disease was studied and it was found to be most preva- 

 lent in the season at which children make their most rapid growth. 

 "As xerophthalmia is caused by the absence of something essential 

 to growth, it is logically to be expected that the disease will predomi- 

 nate during the part of the year when the organism consumes the 

 largest quantity of this lipoid material (vitamin A) for its growth, 

 as is here found to be the case. It is also suggested that the specific 

 lipoid (vitamin A) may be necessary for the formation of antibodies 

 against infection and may be continually used up in this process as 

 well as in growth." 



Still more recently, Bloch (1926) has reported observations upon 

 two patients, a brother and sister, who came under his care both 

 suffering from xerophthalmia and night blindness. Light baths had 

 no curative efifect whereas the girl recovered when given cod-liver oil 

 and other vitamin-A-containing food. Here it was quite certain that 

 the human eye disease was curable by dietary treatment and that the 

 curative substance was vitamin A and not the antirachitic factor nor 

 anything which the light-treatment could supply. The brother appar- 

 ently could not absorb vitamin A normally from his digestive tract, 

 for he was not cured until given cod-liver oil subcutaneously. 



That lack of vitamin A may lead to weakness or abnormality of 

 other tissues as well as those of the eye, has been shown by the work 

 of several investigators. Osborne and Mendel (1921a) refer to diarrhea 

 and diminished appetite as frequently resulting from this lack ; and they 

 have definitely correlated it (1917d) with the occurrence of phosphatic 

 renal calculi among their experimental animals. McCollum (1917) and 

 also Drummond (1919b) early reported increased susceptibility to 

 infections of the respiratory system. 



Steenbock, Sell and Buell (1921) confirmed this and suggested 

 that the failure to develop the characteristic eye disease in some cases 

 may be due to a measure of immunity acquired through the respiratory 

 infection. As symptoms of the respiratory infection, the incidence of 

 which is regarded by these authors "as part of the syndrome induced 



