i. 235, 236

effect of fresh water on the form of, i. 243

Chorda filum, structure and habitat of, i. 245

Chordaria divaricata, spore cysts of, i. 246

Chordariæ, structure of, i. 245

Chrysophonic acid, whence obtained, i. 303

Chylocladia kaliformis, structure and mode of propagation of, i. 235

Cibotium Barometz, caudex of, i. 350

Cidaris, spines of the, ii. 180

Cinchoneæ, alkaloids obtained from, i. 427

Cinchonine, structure of, and whence obtained, i. 427

Cirripedia, characters of the, ii. 213

Cladocarpi, characters of the group, i. 328

Cladocera, characters of the order, ii. 208

Cladonia, structure of, i. 306

Cladophora, structure of the genus, i. 222

Cladophora pellucida, structure of, i. 222

Claudea, structure of, i. 242

Clavariei, structure and habitat of, i. 266

Clio pyramidata, structure of, ii. 242, 243

Cliona, structure and burrowing apparatus of, ii. 60

Clione borealis, structure and habitat of, ii. 243 fossil remains of, ii. 244

Closterium, double circulation of the internal fluid in, i. 193

Closterium lunula, structure and development of, i. 193

Cloud, force of the chemical combination requisite to form a, i. 98

Cloves, oil of, amount of radiant heat absorbed by the perfume of, i. 44

Club mosses. _See_ Lycopodiaceæ

Coal, i. 13 effect of the consumption of a pound of, in a steam-engine, i. 29, 30 energy in abeyance in the coal existing in the whole globe, i. 30

Coal gas, i. 117, 118 poisonous quality of, i. 118 explosive quality of, i. 118 impurities from which it is freed, i. 118 uses of the black fœtid gas water resulting from the distillation of coals, i. 119

Coal tar, i. 120 substances produced from, by distillation, i. 120 colours, i. 121, 122

Cobalt, i. 4, 5 crystals of, formed artificially by electricity, i. 74 effect of heat in the magnetism of, i. 77

Coccocarpei, characters of, i. 307

Coccocarpia smaragdina, section of, i. 300

Coccospheres, found at a vast depth in the ocean, ii. 51

Cockle, structure and mode of life of the, ii. 230, 231

Codium, structure and habitat of, i. 219-224

Codium Bursa, structure of, i. 224

Codium tomentosum, structure of, i. 214

Coffee, active principle of, i. 428

Cohesion, properties of, i. 25 in solids, i. 25 in liquids, i. 25

Cohesion: reciprocal attractions between solids and liquids, i. 25 instance of the power of the cohesive force, i. 91

Colchicum, or meadow saffron, mode of reproduction of, i. 388 poisonous alkaloid obtained from, i. 427

Collemacei, structure and habitat of, i. 307

Colloid bodies, i. 109, 110 less diffusible than crystalloids, i. 109 permeable to solutions of crystalloids, but impermeable to solutions of colloids, i. 110 characteristics of colloids, i. 111

Collomia grandiflora, fructification of, i. 380

Colocasia, water secreted by, i. 430

Colour, causes of, in flowers, green leaves, dyed cloth, gold, and copper, i. 35, 36

Colouring matter of flowers and plants, i. 428, 429

Comatula, structure of, ii. 175, 176

Combination, chemical, i. 94 the law of definite proportions, i. 94, 95 force of, i. 97, 98

Combustion, effect of, in the consumption of coal in the steam-engine,