PRESENT-DAY KNOWLEDGE OP VITAMINS 99 



by appropriate foods. Beriberi occurs frequently in Asiatic coun- 

 tries where rice is the staple article of food. The unquestioned 

 prevalence of the disease among rice-eating people led to the 

 theory that a fungus or 

 bacterial growth in rice 

 might be the cause of this 

 disease. However, a de- 

 ficiency in the vitamin diet 

 is now generally held to be 



+V naneo nf tlii'c rli'c^ac^ Funk fed pigeons of the same age the same amounts 



tne cause 01 tnis disease. of rice> The one on the left ate whole rice The one 



Prpcpnt Hflv IrrmwlArlo-A on the ri S ht was fed polished rice which lacks vita- 



,sem aay Knowieage min B ^ he second p . geon . g showing ^#^3 O f 



Of vitamins. The experi- polyneuritis which can be cured by feeding it foods rich 



in vitamin B. Polyneuritis is also found in people. 



ments performed in the 



last few years have given us considerable knowledge of vita- 

 mins. Unless we include them in the diet, deficiency diseases 

 may result. 



An interesting experiment was carried on to determine the diet 

 essential for the normal development of rats. Baby rats were fed 

 equal amounts of food with proper kinds and proportions of pro- 

 teins, carbohydrates, and mineral matters, but one group was given 

 fat in the form of lard and the other given butter instead of the 

 lard. The rats fed on lard failed to grow normally and they soon 

 developed sore eyes. The butter-fed rats grew into normal 

 healthy rats. Lard lacks the vitamin known as the fat-soluble 

 vitamin A. This vitamin occurs in milk, butter, cod-liver oil, egg 

 yolk, and in the leafy green parts of vegetables such as spinach, 

 lettuce, and cabbage, and in the yellow pigmented parts of plants 

 such as carrots and sweet potatoes. The lack of vitamin A causes 

 stunted growth, and a certain eye disease, xerophthalmia, which 

 may result in permanent blindness. Taken in its early stages, 

 however, this disease can be cured by including in the diet some 

 foods containing vitamin A. 



In another experiment, two groups of pigeons were fed, one on 



