NOTICES OF NEW BOOKS.
The Government of the United States of America is to-day a greater scientific publisher than that of any other State in the world. Its voluminous Reports are also scattered with the greatest generosity in every scientific centre, and though the term "exchange" is used, the actual debit must be largely on the side of our American cousins. We have just received the above, consisting of 880 pages, strongly bound and beautifully illustrated, and though of the greatest importance to the agriculturist, its zoological information is not inconsiderable. In noticing three contributions only, it must be understood that they appertain to our special studies, and are for that reason selected.
"Some Examples of the Development of Knowledge concerning Animal Diseases" is the title of a contribution by Mr. D.E. Salmon. This paper is necessarily largely pathological, but it is a full and excellent résumé of the evolution of scientific methods and discoveries; while its estimate of the earlier theories as structures without stability, representing "the individual workings of the philosopher's mind rather than the truths of nature," will apply to much thought of the present day.
"Progress in Economic Entomology in the United States" is the subject of a paper by Dr. L.O. Howard. At the beginning of the present century the United States, with its population of only 5,000,000, and its restricted husbandry, suffered comparatively little from the attacks of insects on its crops. But now the conditions are vastly altered. Increased cultivation has been accompanied by a multiplication of plant-eating insects; many pests have been imported; and now, as "the century has grown older, the need of remedies against insects has grown greater." The State has not, however, neglected its duties. "During the
