together into synoptical form our knowledge of groups of varieties. These groups are then discussed separately. The problems of factory building, factory organization, buying and testing milk, and the proper marketing of cheese, are briefly discussed. Such a discussion should be useful to the student, to the beginner in cheese-making, as a reference book on many varieties in the hands of makers who specialize in single varieties, and to the housekeeper or teacher of domestic science. The material has been brought together from the experience of the writers, supplemented by free use of the literature in several languages. Standard references to this literature are added in the text. No introduction to the subject of cheese should fail to mention the work of J. H. Monrad, who has recently passed away. Mr. Monrad never collected his material into a single publication, but his contributions to cheese-making information, scattered widely in trade literature over a period of thirty years, form an encyclopedia of the subject. Bulletins of the Agricultural Experiment Stations and United States Department of Agriculture have been quoted extensively, with citation of the sources of the material. Personal assistance from Professor W. A. Stocking and other members of the Dairy Department of Cornell University, and C. F. Doane of the United States Department of Agriculture, is gladly acknowledged. Students cannot learn out of books to make cheese. They may, however, be aided in understanding the problems from such study. To make cheese successfully they must have intimate personal touch with some person who knows cheese. Sympathetic relations with such a teacher day by day in the cheese-room are essential to success in making cheese which, at its best, is one of the most attractive of food-products. THE AUTHORS. TABLE OF CONTENTS CHAPTER I PAGES GENERAL STATEMENT ON CHEESE 1-4 Nature of cheese, 1; Cheese-making as an art, 2; Cheese-making as a science, 3; Problems in cheese-making, 4; History, 5. CHAPTER II THE MILK IN ITS RELATION TO CHEESE 5-28 Factors affecting the quality, 6; Chemical composition, 7; Factors causing variation in composition, 8; Milk constituents, 9; Water, 10; Fat, 11; Casein, 12; Milk-sugar, 13; Albumin, 14; Ash, 15; Enzymes, 16; The flavor of feeds eaten by the cow, 17; Absorption of odors, 18; Effect of condition of the cow, 19; Bacteria in the milk, 20; Groups of bacteria in milk, 21; Acid fermentation of milk, 22; Bacterium lactis-acidi group, 23; Colon-aërogenes group, 24; Acid peptonizing group, 25; Bacillus bulgaricus group, 26; Acid cocci or weak acid-producers, 27; Peptonizing organisms, 28; Inert types, 29; Alkali-producing bacteria, 30; Butyric fermenting types, 31; Molds and yeasts, 32; Bacterial contamination of milk, 33; Germicidal effect of milk, 34; Sources and control of bacteria in milk, 35; The cow, 36; Stable air, 37; The milker, 38; Utensils, 39; The factory, 40; The control of bacteria, 41; Fermentation test, 42; The sediment test, 43. CHAPTER III COAGULATING MATERIALS 29-40 Ferments, 44; Nature of rennet, 45; Preparation of rennet extract, 46; Pepsin, 47; Chemistry of curdling, 48; Use of acid, 49; Robertson's theory, 50; Rennet curd, 51; Hammarsten's theory, 52; Duclaux theory, 53; Bang's theory, 54; Bosworth's theory, 55. CHAPTER IV LACTIC STARTERS 41-54 Acidifying organisms, 56; Starter, 57; Natural starter, 58; Commercial starter or pure cultures, 59; Manufacturer's directions, 60; Selecting milk, 61; Pasteurization, 62; Containers, 63; Adding cultures, 64; Cleanliness, 65; "Mother" starter or startoline, 66; Examining starter, 67; Second day's propagation, 68; Preparations of larger amount of starter, 69; Amount of mother starter to use, 70; Qualities, 71; How to carry the mother starter, 72; Starter score-cards, 73; Use of starter, 74; The amount...