Familiar Lectures on the Physiology of Food and Drink. By
R. J. Mann, M.D. (Ward, Lock, and Co.)—This is an interesting book, which, after our first cursory inspection, we felt inclined to praise highly. Indeed, the greater number of the lectures here printed deal with important physiological processes in the human body not only clearly, but accurately. The blood, its functions and circulation, the liver and secreting organs, the structure of muscles and nerves, and the action of the kidneys and the skin, are discussed in a popular, yet satisfactory manner. Much of what is said about alcohol and the effects of intemperance may be similarly commended. Bat on submit- ting many of the more purely chemical statements in this volume to careful examination, we find that they are obsolete or inaccurate, while much of the vegetable physiology here offered must be condemned for the same reasons. Thus, on page 15, we find the extraordinary statement that all the solid matter of vegetation is derived from water absorbed by the roots, although the carbonic acid introduced by the foliage and other green parts is, in fact, the chief source of the substance of plants. The origin of all the nitrogen of vegetation is wrongly assigned to ammonia on page 37, where, moreover, the weight of ammonia conveyed annually to the ground in rain is enor- mously exaggerated. Then, again (page 29), a pair of human lungs is said to give out into the air, in a single hour, no less than 586 grains of carbon ; one-fourth of this quantity would be nearer the truth. It is a pity that errors such as these should disfigure a book which in plan and style presents many commendable features.
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