Page:The American Cyclopædia (1879) Volume XIII.djvu/502

 486 PHYSIOLOGY PHYTELEPHAS phenomena are exactly the same with those which are to be seen in the inorganic world ; on the contrary, they are peculiar in their details, and can only be met with in living bodies, because there only are the necessary conditions for their production. But this pe- culiarity is merely one of detail, not of their essential character ; consequently they are to be studied in the same way as similar phe- nomena elsewhere. The temperature of the blood is to be ascertained by the thermome- ter, like that of any other fluid; the gases absorbed and exhaled in respiration are to be analyzed and measured in the same way as if they came from any other source ; but all these experiments and investigations, to be successful, must be performed upon the living body, since it is in the living body alone that the necessary conditions of the vital pheno- mena exist, even the simplest. On the other hand, there is a second division of the vital actions, in which the phenomena are apparent- ly different from those of the inorganic world, and accordingly require to be studied in a peculiar manner ; these are the phenomena of the nervous system, and consist of the various forms of sensibility, the motor stimulus, reflex action, and the sympathetic relation between various organs and parts of the body. It is evident, of course, that these phenomena also must be studied by observations made upon the body during life, or at least before the vitality of the nerves and nervous centres has disap- peared. The third and last division of the vital functions is perhaps the most peculiar of all, and the most widely removed from the phe- nomena presented by inorganic bodies ; these are the actions which relate to reproduction or the generation of young individuals. These phenomena, unlike those of the first two divi- sions, do not relate to the preservation of the individual, but to that of the species. They consist of the appearance of a succession of different forms by which the embryo is de- veloped into a perfect organization, and in which life is transmitted by an unbroken series of parents and progeny. Nothing similar to this is ever seen in the inorganic world, and accordingly the phenomena of this kind form the most striking characteristic of beings en- dowed with life. The vital phenomena are also sometimes divided in a different manner, into those of vegetative and those of animal life. The vegetative functions are those which are common to both the animal and vegetable kingdoms, and include those relating to the internal nutrition and growth of the body and the reproduction of the species. All the phys- ical and chemical changes going on in the blood and the tissues, secretion, the formation and elimination of excrementitious material, the production and growth of the egg and the embryo, and the changes in the body which show themselves at different periods of life, belong to the phenomena of this class. The animal functions consist in the phenomena of sensation, consciousness, intelligence, of vol- untary or excited motion; all those in fact which bring the animal into relation with the external world through the operation of the nervous system. The functions concerned in the vital processes are treated under ABSORP- TION, ABSTINENCE, ADIPOSE, AGE, ALIMENT, ANIMAL, ANIMAL ELECTRICITY, ANIMAL HEAT, BILE, BLOOD, BONE, BRAIN, CAPILLARY VES- SELS, CARTILAGE, CELL, CHYLE, CHYME, CIRCU- LATION, COMPARATIVE ANATOMY, DENTITION, DIETETICS, DIGESTION, EMBRYOLOGY, GLAND, HEART, HISTOLOGY, HUNGER, KIDNEY, LIVER, LUNGS, LYMPH, MUSCLE, NERVE, NERVOUS SYSTEM, NUTRITION, PERSPIRATION, EESPIRA- TION, SECRETION, SKIN, VOICE, &c. Besides the authors above named, reference may be made to the writings of Sir Charles Bell, Todd and Bowman, Carpenter, Magendie, Tie- demann and Gmelin, Burdach, Mtiller, Wagner, Virchow, B6rard, Flourens, Longet, Bernard, Robin, Brown-Sequard, and Milne-Edwards in Europe, and in America to those of Dunglison, Draper, Dalton, and Flint. PHYTELEPHAS (Gr. fwfo, a plant, and eM- 0af, elephant), the botanical name of the ge- nus which produces the ivory nut or vegetable ivory. It was formerly placed in the palm family ; but as it differs essentially from the palms in the structure of the flowers, it now forms, with one other South American genus, a separate order, the pliytelepTiasiecB. The ge- nus contains two if not more species, the most important of which is P. macrocarpa, which furnishes the ivory nuts of commerce. The tree is found in the northern parts of South Vegetable Ivory Tree (Phytelephas macrocarpa). America, where on the banks of streams and in other damp localities it forms distinct groves, other trees, shrubs, or even herbs being hardly ever mixed with it. The proper stem creeps along the ground for 20 ft. or more, and th< ascends, the upright portion being seldom over