44 RESEDA. RESTHARROW. 
ek Puimergsuras, aeee Sub-genera, 4. Orper V. 
92. Oplocephalus, Cuv. 100. Rana, Z. 
93. Acanthophis, Daud. 101. Megophrys, Kuhl. WEE Gre 
94. Echis, Merr. 102. Ceratophrys, Bote. ELeventH Famity 
poy menea nan sanig. Sub-genera, 2. AMPHIUMIDA, 
6 Crotalina, 103. Dactylethra, Cuv. “ 
96. Trigonocephalus, Oppel. 104. Breviceps, Merr. 111. Protonopsis, Barton. 
Sub-genera, 4. 105. Bombinator, Merr, 112, Amphiuma, Garden. 
97. Crotalus, Z. 106. Pipa, Lauren. 
Sub-genera, 2. 107. Bufo, Lauren. 
108. Rhinellus, Fitz. TWELFTH FAMILy. 
EreutH FAMtIny, Sub- genera, 3. SIRENID4 
Ca CILIDA., : 
98. Cecilia, L. q Froteina: 
DERG eid 113. Axolot, Cuv. 
roar nasuni Cras) URODELA. 114. Proteus, Laur. 
AMPHIBIA, 109. Salamandra, Lauren. BD: Nec eunae re oeeesa ee. 
Sub- » oO. ireni 
Orver IV. a, see Jaw aN a 
ANOURA., 116. Siren, Z. 
99. Hyla, Zaur. 
RESEDA. A genus of thalamiflorous plants, 
nearly allied to the Crucifere, but differing from 
them in the stamens being indefinite, the cap- 
sules unilocular, and the seeds without an um- 
bilical cord; and it constitutes an order of its 
own under the name of Resedacew. One species 
grows wild in Britain; and upwards of 20 species 
have been introduced from Continental Europe, 
Africa, and the Levant. But only two species 
possess any considerable interest; and these are 
noticed in the articles Drzr’s Wrxp and Mic- 
NONETTE. 
RESERVOIR. A contrivance for accumulat- 
ing and retaining meagre supplies of water. The 
chief kinds of it required for agricultural pur- 
poses are the pond and the dam. See the arti- 
cles Ponp and EMBANKMENT. 
RESIN. A vegetable substance, which exudes 
from many trees, either from natural fissures or 
artificial wounds. Common resin, or rosin, is 
obtained by distilling the exuded matter of some 
species of pine; oil of turpentine passes over, 
and the resin remains behind. The resins are 
insoluble in water, but soluble in alcohol, and 
inodorous, though they sometimes derive odour 
from containing an essential oil. They consist 
chiefly of carbon, with about one quarter of oxy- 
gen and hydrogen. 
RESP. See Rap Water. 
RESPIRATION. The alternate inspiration 
and expiration of atmospheric air, for the pur- 
pose of bringing it into contact with the blood, 
and exchanging the hydrogen and carbon with 
which it is charged, for oxygen. This function 
is therefore closely connected with that of the 
circulation of the blood. The organs and me- 
chanism by which this wonderful function is 
carried on, vary considerably in the different 
classes of animals. In the mammalia, birds and 
reptiles, the organ of respiration is the lungs; 
in fish, the gills; in most insects, the trachee ; 
and in the lower classes of animals, different 
parts of the system. The air, being brought into 
Sub-genera, 2. 
contact with the blood, is decomposed, its oxygen 
is united with the blood, and its nitrogen is re- 
turned by expiration, unchanged, with an addi- 
tion quantity of carbonic acid gas, 
the oxygen of the inhaled air is united in the 
lungs with the free hydrogen, and forms water, 
which is emitted in the form of vapour, visible 
at 40° Fahr. Another part of the oxygen unites 
with the superfluous carbon in the blood, and 
forms the carbonic acid gas, which passes off with 
the watery vapour. It is evident from observa- 
_ tion, that oxygen gas is necessary to animal life. 
As to its manner of operating in the body after 
inspiration, opinions differ. Upon respiration 
depends also animal heat, which is greater, at 
least in the mammalia and in birds, than that 
of the surrounding element. The mechanical 
part of the function of respiration is effected by 
the action of the ribs and diaphragm. In the 
natural state, the ribs are inclined downwards, 
and when this series of moveable hoops is raised 
by the action of the muscles, the cavity of the 
chest is enlarged. The descent of the diaphragm 
by its contraction increases this effect, and the 
air therefore rushes in to fill up the vacant 
space ; the ribs then descend, and the diaphragm 
rises, and the air is necessarily driven out in | 
consequence of the resulting contraction of the 
chest. About twenty respirations take place in 
a minute, and from thirty to forty cubic inches 
of air are inhaled at each inspiration. A man 
consumes about a gallon of air in the same time. 
RESTHARROW,—botanically Ononis. A di- 
versified genus of plants, of the lotus division 
and genista subdivision of the leguminous order. 
One species grows wild in Britain; about 60 spe- 
cies have been introduced from other countries; 
and about 50 other species are known. About 
one half of the introduced species have yellow 
flowers ; and most of the others have either pink 
or purple flowers, Some are evergreen under- 
shrubs; some are annuals; a few are creepers; 
and a few are radical herbaceous perennials, 
A part of 
