The preservation of milk and cream for general household purposes, the A scheme for paying for cream by the Babcock test in butter factories, J. M. A new butter package. Page. 896 898 897 AGRICULTURAL ENGINEERING. Seepage or return waters from irrigation, L. G. Carpenter.... STATISTICS. Seventh Annual Report of Georgia Station for 1894. Seventh Annual Report of Kentucky Station for 1894. Reports of director and treasurer of Maine Station, 1894. Report of director of Pennsylvania Station for 1894, H. P. Armsby. Reports of director and treasurer of Rhode Island Station, 1894. LIST OF PUBLICATIONS ABSTRACTED. Experiment stations in the United States: Bulletin 67, November, 1895... 898 900 900 900 900 900 900 Alabama College Station: Colorado Station: Bulletin 33, January, 1896.. Georgia Station: Bulletin 29, October, 1895.. Seventh Annual Report, 1894. Kentucky Station: 893 898 859 900 853, 854, 856, 860, 862, 863, 866, 867, 868, 872, 875, 876, 879, 884, 887, 893, 898, 900 Massachusetts Hatch Station: 854 Special Bulletin 36, April 11, 1896.. State Weather Service Bulletin 74, November 30, 1895. State Weather Service Bulletin 75, December 31, 1895. State Weather Service Bulletin 76, January 31, 1896. State Weather Service Bulletin 77, February 29, 1896. Oklahoma Station: 845 845 845 845 848, 849, 850, 851, 854, 857, 858, 862, 873, 875, 876, 889, 891, 900 Monthly Weather Review, Vol. XXIII, No. 8, August, 1895. 817 869 840 814. 844 844 EXPERIMENT STATION RECORD. VOL. VII. No. 10. In connection with investigation of the laws of nutrition and their application to the economy of the food and feeding of man and domestic animals, of feeding and the use of food, studies of the changes which the nutrients of the food undergo in the body, and the ways they are utilized, are of fundamental importance. Such studies include respiration and metabolism experiments on live subjects, and have to do with some of the most intricate and difficult kinds of investigation. In the ordinary digestion experiment the nutrients consumed and those excreted in the dung are determined and the difference is taken as that digested. In experiments on the metabolism of nutrients the total income and outgo of materials are measured, and to do this it is necessary to take into account not only the nutrients digested and resorbed but also the oxygen used in respiration, and the excretions of both the kidneys and intestines. Another phase of the question is the metabolism of energy. studying this it is necessary to take into account the energy of the food and drink consumed and of the excretory products, the heat radiated and the exterior mechanical work performed. Experiments on the metabolism of matter must precede those upon the metabolism of energy, both because the former offer the more immediate and practical results and because the data they give are necessary as a basis for the other. The primary data are the amounts of nitrogen, carbon, hydrogen, and other elements involved in the bodily income and outgo. The starting point is the nitrogen balance. The elaboration of methods for such investigation has been the work of years, and the apparatus used is among the most interesting devices of modern experimental science. To facilitate reviewing the work already done in this line and comparing the results, a compilation of metabolism experiments with both man and animals is being made in this Office. A surprisingly large amount of data on this subject has been found, and already over one thousand such experiments with man, and about the same number with domestic animals, have been compiled. It is proposed to group this material under appropriate heads, according to the character of the work, for more critical examination and study, and ultimately to publish at least a digest of the work, with discussion, in a bulletin. It is believed that such a review of this important line of investigation will throw much light on the accepted theories of nutrition, and may sug gest new fields for profitable investigation. The historical article in the present number of the Record reviews one of the fundamental questions concerning the excretion of metabolized nitrogen. This is intended to serve as an introduction to a subject to which the Office proposes in its nutrition investigations to devote a large share of attention in the future. In connection with these inves tigations it is planned to study the metabolism of nutrients and energy, using a modified form of apparatus, with a view to aiding in the eluci dation of the laws and principles upon which real progress in the use of foods depends. The institutions for agricultural education and research in Europe are to be the subject of personal study by a representative of this Office during the present summer. Dr. A. C. True will spend some time abroad, and will visit many of the more prominent of these institutions. The general systems of agricultural instruction in the different countries will be studied; and the equipment, courses of study, methods of teaching, etc., of the various kinds of agricultural schools and institutions will receive special attention. The administration and work of the experiment stations will likewise be investigated. In view of the inquiry undertaken by the committee on courses of study of the Association of American Agricultural Colleges and Experiment Stations, the collection of information in regard to agricultural education abroad would seem to be especially opportune. It is expected that the results of Dr. True's observations will appear later in publications of the Office. THE EXCRETION OF METABOLIZED NITROGEN BY ANIMALS. C. F. LANGWORTHY, PH. D. The fundamental subject which underlies inquiry on the nutrition of animals, both abstract and practical, is metabolism, or the chemical and physical changes which matter and energy undergo within the animal organism. The processes of metabolism of matter include those by which the constituents of the food are transformed within the organism into more complex or simpler compounds which are used to build up the body and repair its wastes, and finally excreted when they are no longer useful to the organism. Parallel with these processes are those of the metabolism of energy, by which the potential energy of the food is changed into those forms of energy which are needed for physiological work within the body, e. g., that of respiration, circulation, and digestion, for exterior muscular work, and for furnishing the heat which is necessary to maintain life. In experiments upon the metabolism of matter in animals the essential feature is the balance of income and outgo. This may be expressed in terms of the raw materials, food and drink, the oxygen of inhaled air, and the excretory products, solid, liquid, and gaseous. It is also expressed in terms of chemical compounds of which these products are composed, e. g., the water and nutrients of food and the excretory products which come from their metabolism. For accurate experimenting, however, the income and outgo must be determined by the quantities of chemical elements, nitrogen, carbon, hydrogen, oxygen, sulphur, phosphorus, etc. The metabolism of energy is expressed in terms of heat. The importance of the nitrogenous compounds of the food makes the metabolism of nitrogen one of the most essential of the processes of nutrition. In all metabolism experiments, therefore, the determination of nitrogen is of fundamental importance. It is commonly assumed that where the nitrogen balance is measured by determinations of nitrogen in the food and drink on the one hand and of the excretions of the kidneys and intestines on the other, an accurate balance of income and outgo is obtained. It has, however, been claimed that some of the excretory nitrogen leaves the body in the form of gas; in other words, that some of the nitrogenous material of the food or of the body substance may be so decomposed in the body that nitrogen is liberated and leaves the body in the free state. If this supposition is correct, all of the experimenting thus far done is defective, and our whole theory of nutrition in so far as it is based upon inquiries in metabolism requires |