XVIil INTRODUCTION. 
tinuous, membranous, branched tubes, to receive, contain, and direct the 
nutritive juices, from the organs where they are prepared, till they are 
required for the purposes of nutrition, respiration, vr the secretions. 
5. The glandular tissue includes those secreting organs which pro- 
duce fluids for internal use, or to transmit them out cf the body, by 
means of excretory canals. These organs have a granular or lobated 
form. 6. The bony tissue, or cartilaginous, calcareous, and corneous, 
is formed by the mucous, or gelatinous parenchyma, in which are 
deposited the hardest and most resisting parts, which protect the body 
and contribute to its motion. 7. The fibrinous or muscular tissue is 
composed of filaments disposed in bundles, which, from their power of 
contraction, produce all the movements which characterize animals. 
8. The zervous tissue is a net-work of filaments and tubes, in the 
interior of which are found prolongations of the cerebral matter. 
This tissue, extending from the centre to the circumference, like radii 
from a centre, is the medium of sensation,—actuates every member 
through the medium of volition, and connects all the parts of the body 
by a mutual sympathy. 
The animal fluids are found in the body under the form of gases, or 
liquids, of various consistence. The first being absorbed, or exhaled, 
are but momentarily under this form. The fluids are the chyme, the 
chyle, the lymph, the blood, and the serous, albuminous, mucous, 
saline, and other humors, peculiar to different parts of the body. 
The simple chemical elements which are found in the animal struc- 
ture, are among the imponderable agents, caloric, light, and the 
electric fluids. Among the simple gases, azote, which enters into the 
composition of many of the tissues; hydrogen, which is one of the 
elements of lymph, bile, &c.; oxygen, which all animals absorb in 
the act of respiration; carbon, lime, sulphur, iron, &c., which serve as 
the base of many salts, formed by carbonic and phosphoric acid. 
The instincts and habits of the different classes of animals will be 
hereafter detailed, in the descriptions of the individual species, whose 
manners have been most accurately observed. It is sufficient, in tnis 
place, to state, that all their motives to action, their migrations, and 
their instincts, may be traced to the desire of self-preservation, and the 
impulse of reproduction. 
The Vecretaste Kinepom is sufficiently distinguished from the 
animal, as before remarked, by its passive character, by the wavt of 
spontaneous motion, and of sensation. Vegetable life is. therefore 
supported by absorption ; and its functions, like those of animals, are 
