The quantity and complexity of scientific information is steadily increasing, and students are already overburdened with material to remember. Furthermore, the mere recital of facts does not increase one`s understanding of general principles. Efforts have been made to avoid overburdening the students with information. Many of the omissions are international to make the text selective. The author`s primary goal has been clear writing and meaningful figures. Yet, he has remained rigorous in his coverage of topics, believing that excess detail cannot be equated with rigour. The book is profusely and attractively illustrated with line drawings and fine tables. I hope that this work will serve the students and teachers as an indispensable source book. The book contains twenty two chapters and many of them are chiefly emphasized. These include - Vitamins, Feeding and Digestion, Respiration, Endocrinology, Excretion, Circulation, Nervous System, Reproduction, Muscular contraction and Thermal Regulation. Contents : 1. Introduction 2. Protoplasm 3. Structure of Cell 4. Chemical Bonds 5. Water 6. pH and Buffer Solution 7. Mineral Elements 8. Feeding and Digestion 9. Vitamins 10. Enzymes 11. Metabolism 12. Respiration 13. Blood 14. Physiology of Circulation 15. Excretion 16. Muscles 17. Endocrinology 18. Nervous System 19. Receptors 20. Reproductive System 21. Temperature Regulation 22. Regulation of Body Fluids and Electrolytes