54 THE BOTTOM OF THE SEA. 



Stratum of air and water, and they reach their maxi- 

 mum development where the two atmospheres meet.* 

 When a volcanic eruption takes place in the sea, 

 the composition of the gases contained in the 

 water is necessarily changed in the neighbourhood 

 of the volcano by the subterranean emanations. 

 Some seas, like the Caspian, are literally poisoned 

 by volcanic products, and this to such a degree that 

 it is hardly possible to live near them. A bird can- 

 not hover above their waters without the risk of 

 perishing from their deadly influence.! In the great 

 oceans the gases produced by volcanic eruptions are 

 reduced to insignificant proportions by the action of 

 the marine currents. 



* Notwithstanding the general tmth there is in this statement, 

 organised creatures have recently been diseovered in much greater 

 depths than had beeu anticipated. — Tr. 



t This was for a long time the popular notion concerning the 

 Dead Sea. The fact is now known to be otherwise. INIr. Tristram, 

 in that chapter of his interesting journal where he describes " the 

 Dead Sea shore," mentions having seen a fine brown-necked raven, 

 which flew quite across tlie lake, and a kingfisher actually sitting on 

 a dead bough in the water. Many gulls were also fishing in their 

 customary manner ; small flocks of pochard ducks skimmed the 

 surface, and close along the shore were dutdius, redshanks, and 

 wagtails, and one specimen of the desert wheatear. At tlie same 

 time, he says, " it is quite certniu that no form of cither vertebrate or 

 molluscous life can exist for more than a very short time in the sea 

 itself, and that all that enter it arc almost immediately poisoned aiid 

 salted down." — Tr. 



