CONTENTS 



PAGH 



Historical 17 



The Physiology of Lactation 32 



Definition of milk, 32 — Location of mammary glands, 33 — Develop- 

 ment of the mammary gland, 34 — Formation of the secretion, 34 — 

 Relation of colostrum to secretion, 36 — Theories of lactation, 37^ 

 The secretion of milk, 40 — Duration of the lactation period, 43 — 

 The total quantity of milk produced during a lactation period, 44 — 

 The cow's udder, 45 — The quantity and quality of milk produced by 

 cows, 49 — Bibliography, 50. 



The Physical Properties of Milk 61 



Microscopic study of milk, 51 — Creaming, 52 — Cellular elements in 

 milk, 57 — The nature of the fat globules, 60 — Colostrum, 62 — Proper- 

 ties of normal milk, 63 — Odor and taste, 64 — Viscosity and cohesion, 

 64 — Specific gravity, 65 — Freezing-point, 67 — Electric conductivity, 

 67— Refractivity, 67— Specific heat, 68— Bibliography, 69. 



General Chemistry of Milk 70 



Composition of milk, 70 — Composition of colostrum, cream, skimmed 

 milk, whey, buttermilk, 73 — The physiologic origin of milk constit- 

 uents, 75 — Origin of casein, lactalbumin, and globulin, 75 — Origin 

 of butter-fat, 76 — Origin of milk-sugar, 78 — Origin of mineral con- 

 stituents, 78 — The chemistry of butter-fat, 78 — The decomposition 

 of butter-fat, 81 — The chemistry of casein, 82 — Properties of bovine 

 casein, 86 — Rennet coagulation, 90 — Conditions governing rennet 

 action, 93 — Lactalbumin, 97 — Laotoglobulin, 98-r-Mucoid protein 

 or lactomucin, 98 — Other proteins in milk, 98 — Lecithir and cephalin, 

 99 — Nitrogen-containing extractives, 99 — Milk-sugar, 99 — The min- 

 eral constituents of milk, 101 — Gases in milk, 102 — The reaction of 

 milk, 104 — Variability in the composition of milk, 105 — Difference 

 in composition due to breed, 106 — Difference due to individuality, 110 

 — Variation in composition during the lactation period, 114 — Influ- 

 ence of food on milk, 123 — Influence of weather and temperature on 

 milk, 126 — Exercise and nervous influences, 127 — Influence due to 

 the skill of the milker, 127 — Changes in composition of milk, 128 — 

 Spontaneous changes, 128 — Freezing of milk, 12S — Influence of heat 

 on milk, 131 — Centrifugation of milk, 132 — Dilution of milk, 133 — 

 Dialysis, 133— Electricity, 133— Bibliography, 134. 



The Physical and Chemical Examination op Milk 136 



Sampling, 136 — Composite samples, 140 — The specific gravity, 141 

 — The determination of fat, 147 — Ether extraction of fat, 147 — 

 Refractometer method, 148 — The Babcock method, 155 — Modifica- 

 tions of the Babcock test, 164 — Testing cream by the Babcock method, 

 167 — Testing skimmed milk, buttermilk, and whey by the Babcock 

 method, 173 — Determination of total solids and plasma solids, 175 — 



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