THE VERTEBRATE ANIMAL — SUBPHYLUM VERTEBRATA 389 



gained by feeding experiments on different kinds of laboratory 

 animals and results applied to human beings. The following outline 

 will give much of the essential information concerning vitamins. 



The Vitamins and Their Characteristics 



I. Vitamin A (C20H30O) — antixerophthalmic — fat soluble. 



(a) Sources: carotene (CjoHBe) a yellow pigment in green plant leaves, 

 carrots, and such plant tissues. Transformation of this pigment into 

 the vitamin which is especially stored in shark, cod, halibut or other 

 fish liver oil, egg yolk, and milk. 



(b) Functions: Influences efficiency and acuity of vision, important fac- 

 tor in regeneration of visual purple of retina, strengthens and pro- 

 motes hardiness in epithelial tissue. 



(c) Effects of Deficiency: Xerophthalmia (lack of tear secretion and dry 

 cornea), and "night blindness" in human. "Nutritional" roup in 

 birds. 



II. Vitamin B* "Complex." 



1. Bj or Thiamin (Ci2Hi,ON4S) — Antineuritic. 



(a) Sources: Germ of wheat and other cereal grains, peanuts, liver, and 

 egg yolk. 



(b) Functions: Promotes tone in alimentary tract, stimulates appetite, 

 essential for normal growth, essential for carbohydrate metabolism. 



(c) Effects of deficiency: Beri-beri (neurodigestive disturbance following 

 diet of polished rice), loss of tonus and muscular activity of digestive 

 tract. Cessation of growth. Polyneuritis develops in birds. 



2. Riboflavin (C^H^oOoN^). 



(a) Sources: Eggs, liver, milk, green leaves, yeast. 



(b) Functions: Necessary for growth, active relation to several enzymes 

 witli intermediate metabolism of food. 



(c) Effects of deficiency: Irritation and inflammation at corners of 

 mouth in human (cheilosis). "Yellow liver" of dogs. "Curl-toe" 

 paralysis of chickens. Dermatitis of turkeys. 



3. Nicotinic Acid (CgHsNOz) — antipellagric. 



(a) Sources: Meat, liver, egg yolk, green leaves, wheat germ, yeast. 



(b) Functions: Produces active "coenzymes" (I and II), balances cel- 

 lular function, 



(c) Effects of deficiency: Pellagra in primates (man and monkeys). 

 Black-tongue in dogs. Swine pellagra. 



4. Be or pyridoxine (CgHuOaN). 



(a) Sources: Milk, liver, cereals, yeast. 



(b) Functions: Necessary for growth. May influence oxidation of food. 



(c) Effects of deficiency: Paralysis in chickens. 



♦There are still other recently discovered fractions of Vitamin B. whose func- 

 tions are specific. 



