38 FUNDAMENTAL PRINCIPLES 



again, may take place from any point on the surface of some of the one- 

 celled animals or may take place through the posterior opening of the 

 alimentary canal in higher forms. 



60. Respiration. — The processes of inspiration and expiration taken 

 together constitute respiration, which includes all gaseous interchanges 

 in the organism. 



61. Anabolism and Katabolism. — The processes beginning with 

 ingestion and ending with assimilation are collectively termed anabolism. 

 Anabolism may be defined as the sum of all processes involved in the 

 building up of the body. The processes beginning with dissimilation 

 and ending with expiration and elimination are collectively termed 

 katabolism. Katabolism may be defined as the sum of the processes 

 having to do with the breaking down of the body and the getting rid 

 of the waste matter resulting from it. Egestion, for reasons given in a 

 preceding paragraph (Sec. 59), does not belong under either anabolism 

 or katabolism. 



62. Vitamins. — It has been found recently that providing the organ- 

 ism with the necessary kinds and amounts of proteins, fats, and carbohy- 

 drates or of salts and water is not sufficient. Something else is needed 

 to enable it to assimilate the organic foods, and that is the presence of 

 vitamins. These are organic chemical substances that occur in certain 

 natural foods. Vitamin A (anti-infective or antixerophthalmic vitamin) 

 is present in many animal fats, milk, butter, yolk of eggs and also in 

 spinach, lettuce, cabbage, sweet potatoes, and soy-bean sprouts and is 

 not destroyed by ordinary cooking. It helps maintain a normal condition 

 of the covering membranes of the eye and respiratory canals. Vitamin 

 Bi (antineuritic vitamin) occurs in fruits, meats, milk, yolk of egg, 

 covering of grains and other seeds, and yeast, and promotes growth and 

 guards the body from certain inflammatory conditions of the nerves. 

 Vitamin C (antiscorbutic vitamin) is found in fresh vegetables and citrus 

 and other fruits and prevents scurvy. Vitamin D (antirachitic vitamin) 

 occurs in fish oils as cod- and halibut-liver oils. It prevents rickets and a 

 deficiency of it leads to an inability to form a properly calcified skeleton. 

 Vitamin E (antisterility vitamin) occurs in green vegetables, wheat germs, 

 egg yolk, and milk and prevents sterility in certain animals. Vitamin G 

 (antipellagric vitamin) is found in milk, eggs, and fresh vegetables and 

 prevents pellagra. 



63. Energy Changes in Metabolism. — The food taken into the organ- 

 ism represents a supply of potential energy. One object of dissimilation 

 is to change part of this into kinetic form in order that the organism can 

 make use of it. This kinetic energy appears mostly as heat and as the 

 mechanical energy exhibited in movement ; a small part appears as electri- 

 cal energy; and in some cases, in very small part, as light, shown in the 

 luminescence of some organisms. Some of this kinetic energy is neces- 



