Following solidly in the tracks of his previous book, The World of Carbon Dr. Asimov, Professor of biochemistry and science-fiction novelist comes to grips in The World of Nitrogen with a vital and intensely interesting aspect of organic life. Underlying his clear text is the welcome assumption that a student of high school age need not be coddled or patronized. His is a meaty book which dares to make demands of his reader in the assurance that there are no placebos for understanding. In his organization of the subject he specifically analyzes nitrogen both in its chemical and general manifestations. There will be sections here which will strain the indifferent student although much of Dr. Asimov's references apply to familiar objects which operate in a frame of reference accessible to the non-technical mind. Vividly written, this is a book which demands and deserves the active participation of the reader, a participation which will be rewarded by a solid sense of understanding of our life and death processes, and of preventative and curative medicine.