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272 The two volumes before us on "Light" and "Heat" are of the usual character. The name of Professor Barrett as editor may be taken as a guarantee that the volumes are accurate in their statements, but we see no evidence that the editorship goes any further. They seem to be ordinary text-books merely reduced in dimensions. Good teachers might use them, we think, with good effect, but good teachers are few, and the best teachers are independent of their books. On the other hand, bad teachers are innumerable—they are the rule, and the real question about primary books is how they work in the hands of incompetent teachers. The best books in these circumstances are those that favor the self-education of the pupil, and release him from the over-meddling of stupid instructors. The books before us, it is needless to say, are not of that order.

the first synthesis of an organic body, urea, was made by Wöhler in 1828, say the authors of this treatise, vital force has been regarded as the result of chemical and physical processes. This has been accepted as satisfactory till the present time, notwithstanding it has been necessary to admit, on a closer consideration, that a clearer definition of the chemical activity by which living protoplasm is governed would be hailed as a very desirable step of progress. The idea that there was a chemical difference between dead and living protoplasm never found expression till 1875, and nearly all physiologists still hold the view that a complete chemical identity exists between them, notwithstanding that it would be hardly possible to explain the cause of life if this were the case. E. Pflüger was the first to assert, in 18*75, in a paper on physiological combustion in living organisms, that a chemical difference must necessarily exist between living and dead protoplasm. One of the authors of this treatise, in verifying an hypothesis he has proposed on the formation of albumen, met with a number of unaltered Aldehyde groups which stood in close relations with the Amidon groups, and immediately conceived the idea that the source of the vital movement in protoplasm was to be sought in the Aldehyde groups with their intense atomic movements, and the origin of death in the passage of the Aldehyde groups into Amidon groups. Shortly afterward both the authors succeeded in demonstrating the real existence of Aldehyde groups in living plasma. The present monograph gives a full and connected account of their experiments, and of the verifications of them.

present monograph is a part of a series on "The History and Present Condition of the Fishery Industries," which is in course of publication under the direction of the United States Fish Commission, in connection with the census. The arrangement of the main part of the work is geographical, beginning with the maritime provinces of Canada, and passing, with copious accounts of the culture and trade in oysters at all important points on the Atlantic coast, to the Gulf of Mexico and the Pacific coast. Chapters follow on the utilization of oyster-shells, and the natural history of the oyster, with notices of the fatalities to which it is subjected. "An Oysterman's Dictionary" offers an entertaining as well as informing collection of phrases and words descriptive of mollusks and other invertebrates of the Atlantic coast. Statistical tables are given in the final chapter.

fur-seal was very often mentioned in the discussions that took place during the negotiations for the acquisition of Alaska, but very little was known of it, and it was hardly represented in the best zoological collections. The author of this monograph became interested in the subject, and in 1872, by the joint action of the Secretary of the Treasury and Professor Baird, was