IXDEX. 273 



Echinodermata: fossil Echinidae, ii. 182, 183 



Echinodermata Holothuroi'dea, structure and mode of reproduction of, ii f 



183 



Echinodermata Sipunculidae, characters of, ii. 186, 187 

 Echinodermata Synaptidae, characters of the order of, ii. 184, 185 

 Echinus, structure of, ii. 176, 177 

 Echinus miliaris, spines of the, ii. 181 

 Ecklonia, structure and habitat of, i. 252 

 Ecklonia buccinalis, structure of, i. 250 

 Ectocarpeae, form, structure, and habitat of, i. 244, 245 

 Ectocarpus pulsillus, fruit of, i. 245 

 Effusion of gases by pressure, i. 109, 110 



Prof. Graham's experiments, i. 113 

 Electricity, i. 30 



permanent and regular current of, over the earth, in the atmosphere 



and in the surface of the earth, i. 31 

 thunder and lightning, i. 31 



force exerted in the creation of the deep, i. 31 

 the voltaic battery and the electro-magnetic induction apparatus, 



i. 31, 32 



reciprocity of action of electricity and heat, i. 31 

 electricity produced by chemical action, and conversely, i. 32 

 intensity of the light and heat of the electric spark, i. 32 



produced by fifty Bunsen elements, i. 32 

 conducting power of charcoal, i. 32 

 air and glass non-conductors, i. 32 

 proof of the correlation of heat and electricity, i. 33 

 motion of the atoms of a conducting wire during the passage of an 



electric current, i. 33 

 effect on a conducting wire of an invariable transit of electricity 



sent from the same pole of an inductive apparatus, i. 33 

 difference between electric and magnetic currents, i. 33 

 influence of electricity on the aggregation of matter, i. 74 

 ratio between the specific heat and weight of the atoms of matter, i. 74 

 influence of magnetism on the stratified appearance of the electric 



light, i. 78 

 extreme heat and light of electric discharges, i. 84 



the arc discharge, i. 84 

 cause of the stratified discharge, i. 85 

 effect of varied intensity on electric discharges, i. 86, 87 

 effect of varied resistance on electric discharges, i. 88, 89 

 varied facility with which substances transmit electricity, i. 90 

 VOL. II. T 



