NUTRITION NUX VOMICA 545 imate principle is raised to a higher potential. This raising of potential by organization, whether in the plant or animal, may be regard- ed as a conversion of force into matter, while the animal metamorphoses of tissue may be regarded as a conversion of matter into force, or more strictly speaking the evolution of force by matter. The precise point at which the vital transformations begin to generate force would be difficult, perhaps impossible, to determine, and probably varies under different circumstances. Thus the absorption of oxygen by the blood globules should be regarded as a force-generating process ; while in the nervous system the evolution of force is to be regard- ed as commencing with the metamorphosis or oxidation of nerve matter. According to the experiments of Bischof and Voigt, it is conclu- ded that all the nitrogenous material which is digested and taken into the circulation is assim- ilated into flesh (not limiting the term to mus- cular fibre, but including all proteine tissues) before it undergoes metamorphosis into urea. The first series of experiments made were with an exclusively meat diet, and the first and most marked effect was an increase in the produc- tion of urea. If, at the time of commencing the experiment, the dog was ill fed and losing in weight, the feeding of a small quantity of lean meat caused such an increase in the waste (metamorphosis) that nothing was stored up and the animal continued to lose weight. An increase in the quantity of meat caused an in- crease in the metamorphosis and a continued loss of weight; but it was found that a contin- ued succession of equal increments was not accompanied by equal increments of metamor- phosis, but that the latter diminished, so that at length a point was reached when the quan- tity of ingesta balanced the amount of meta- morphosis. This condition was established only when the amount of meat eaten by the dog was equal to ^ or ^ of his weight. An increase beyond this caused an increase in weight ; but in a short time another equilibrium was reached, and a succession of increases of weight followed by states of equilibrium occurred, each state of equilibrium occupying a higher level or poten- tial, until at last a point was reached when the animal refused to take the required quantity of food. Then followed a loss of weight and a reduction of equilibrium to a lower level. The cause of the successive diminution in the incre- ments of metamorphosis compared to the incre- ments of food is found in the nearly equable quantity of oxygen present in the blood. In the next series of experiments fat and lean meat were given together, and then fat alone. The adddition of fat to meat produced two dif- ferent effects. The fat did not prevent the increase of metamorphosis which took place when lean meat alone was used, but rather in- creased it ; at the same time, however, on ac- count of its greater readiness to combine with oxygen, it protected the flesh from the action of this agent. It was found that only one ! third as much lean meat was required to main-
- tain equilibrium when fat was added as when
not. Sugar and starch were found to have a similar effect, but in a rather greater degree. These experiments accord with the results of Mr. Banting. (See ABSTINENCE, COKPULENCE, and BANTING.) Ranke found that in man, who is omnivorous, an equilibrium could not be maintained on lean meat alone, and that a loss of weight occurred even when eating the greatest quantity possible ; but by the addition of fat or starch a state of equilibrium or in- crease was easily attainable. The production of fatty matter by insects in excess of the fat contained in their food was established long ' ago by the experiments of Huber on bees, and confirmed by Dumas and Milne-Edwards. The
- experiments also of Boussingault upon pigs,
whose digestive organs resemble those of man, establish the fact that fat is developed in their bodies. His experiments also indicate that fat I may be produced from exclusively nitrogenous | food, although more readily formed from that
- which is simply hydrocarbonaceous. For a
further consideration of the subject, see "Phys- iology of Man," by Austin Flint, jr., M. D. (1866-76): "A Treatise on Human Physiol- ogy," by John C. Dalton, M. D. (latest ed., 1870); and "Principles of Human Physiolo- gy," by W. B. Carpenter (latest ed., 1874). The subject of vegetable nutrition is treated in the article PLANT. NUTTALL, Thomas, an American naturalist, born in Yorkshire, England, in 1786, died at Nutgrove, St. Helen's, Lancashire, Sept. 10, 1859. He learned the trade of a printer, and studied natural history in the United States. He explored the great lakes and the upper branches of the Mississippi, and in 1810 ascend- ed the Missouri as far as the Mandan villages. In 1819 he explored the Arkansas river and the neighboring regions, and published " A Journal of Travels into the Arkansas Terri- tory " (Philadelphia, 1821). He travelled also on the Pacific coast, and published several pa- pers on the shells and plants of that region. From 1822 to 1834 he was professor of natural history in Harvard college, and curator of the botanical garden. Subsequently he returned to England, and lived on the estate of Nut- grove, bequeathed to him on condition that he should reside there. His principal works are : "Manual of the Ornithology of the United States and Canada" (2 vols. 12mo, Boston, 1834), and "The North American Sylva" (3 vols. royal 8vo, Philadelphia, 1842-'9), forming a continuation to Michaux's great work on the forest trees of North America. MIX VOMICA, a name formerly given to some other seeds, but now applied to a drug which is the produce of strychnos nux-vomica, a tree of the family Loganiacece. It is a small tree with opposite, three- to five-nerved, smooth leaves, and terminal corymbs of tubular flowers with a five-parted limb ; the fruit is smooth, about the size and color of an orange, with a
