PRESENT-DAY KNOWLEDGE OF VITAMINS 



99 



Funk fed pigeons of the same age the same amounts 

 of rice. The one on the left ate whole rice. The one 

 on the right was fed polished rice which lacks vita- 

 min B. The second pigeon is showing symptoms of 

 polyneuritis which can be cured by feeding it foods rich 

 in vitamin B. Polyneuritis is also found in people. 



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- 

 ficiencvin the vitamin diet 

 is now generally held to be 

 the cause of this disease. 



Present-day knowledge 

 of vitamins. The experi- 

 ments performed in the 

 last few years have given us considerable knowledge of vita- 

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

 mav 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 

 healthv 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 yelfow 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 



