1XDEX. 287 



Laughing-gas, or protoxide of nitrogen, combination forming, i. 95 

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

 Laurencia dasyphylla, antheridia of, i. 241 

 Laurencia pinnatifida, or pepper dulse, structure, habitat, and mode of 



propagation of, i. 241 



Laurencia tenuissima, antheridia of, i. 241 

 Laurenciacese, characters of, i. 240, 241 

 Laurentian system, ancient formation of the crystallized limestone near 



the base of the, ii. 54 



Lavender, absorption of radiant heat by the perfume of, i. 44 

 Lead, its resistance to electricity, i. 90 



chloride of, spectrum of, i. 146 

 Leathesia, struct are of, i. 245 

 Leaves of plants, structure and functions of, i. 410 

 Lecanora affinis, section of, i. 300 



structure nr.d habitat of, i. 305 

 Lecanora esculenta, habitat of, i. 305 

 Lecidea, characters of the genus, i. 306 

 Lecidea geographica, great age of, i. 306 

 Lecidinei, characters of the order, i. 306 

 Leeches, structure of, ii. 149-151 



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

 Lepadidse, structure of, ii. 213, 215 



Lepas anatifera, structure and mode of reproduction of, ii. 2 1 5 

 Lepidodendron, structure of the fossil, i. 375 

 Lepidostrobus ornatus, structure of, i. 375 

 Lepraliae, structure of, ii. 219 

 Leptopteris, characters of, i. 364 

 Lessonia, arborescent, forests of, i. 251 

 Lessonia nigrescens, structure of, i. 251 



rings of growth of, i. 252 

 Leucobnum, structure of, i. 329 

 Leucobryum glaucum, leaves of, i. 330 

 Leveillea, structure of, i. 242 

 Libanea crab, a parasite of the medusae, ii. 100 

 Lichens, characters and habitat of, i. 298 



two groups of Gymnocarpei and Angiocarpei, i. 299 



horizontal lichens, i. 299 



gonidia, i. 300 



asci, i. 301 



thallus or frond, i. 301 



dyes obtained from, i. 124, 303 



