No. 7.] CAKl'KNTER—DEKP SEA LIFE. 425 



current, is a mere i^tagnunt pool; and tliis is the explanation of 

 the absence of Animal Life except in the shallows. The im- 

 palpable mud, which is slowly settling to the bottom, may also 

 not be without its effect. This is the result of the attrition of 

 soft Tertiary shores, and of the clay brought down by the Khonc 

 into the western basin, and by the Nile into the eastern, the finer 

 particles pervading the entire sea. Corals and Bivalves suffer 

 from it especially. The per-centage of carbonic acid was found 

 to be as high as GO, Avhilst that of oxygen was only 5; this is 

 believed to be due to the organic matter, brought down by the 

 rivers, using up the oxygen. These unfavourable conditions are 

 primarily due to deprivation of the general oceanic circulation, 

 which maintains life at such great depths. 



There seems, however, to be a limit, in respect of depth, to 

 the preservation of animal remains ; due possibly, as conjectured 

 by Prof Thomson, to the solvent power of sea-water at pressures 

 below 2200 fathoms. This may serve to explain the passage of 

 true Glohigerina ooze, first into grey ooze, poorer in calcareous 

 matter, and finally at great depths into red ooze devoid of lime. 

 Moreover, this dissolving of calcareous skeletons at great depths 

 may serve to explain the production of Greensands, such as is 

 now going on along the line of the Agulhas current. These con- 

 sist largely of the internal casts of foraminifera, the sarcode of 

 which has been replaced by glauconite. The importance of such 

 facts to 2;eolo2:ists is immense. It was the examination of a 

 series of casts of similar bodies in a green sillicate, that, years 

 ago, formed the foundation for the lecturer's interpretation of 

 the structure of Eozoon, where there is a replacement of its 

 sarcodic body by a green silicate, viz. serpentine. If the sea- 

 water, under this tremendous pressure, has dissolved away the 

 shells of Foraminifera, after their sarcode has undergone the sub- 

 stitution alluded to, a beautiful application of this kind of re- 

 search to geological phenomena has been brought forward. 



Referring to Ed. Forbes's limitation of marine life to 300 

 fathoms, the lecturer observed that the statement was true of the 

 iEgean, as of the whole of the Mediterranean, where there is 

 abundant life in the littoral zone, diminishing rapidly towards 

 250 fathoms, below which Animal Jiife is almost at zero. 

 Finally it is not a limit of pressure, of heat, or even of food, but 

 the limit of oxygenation, as determined by the presence or ab- 

 sence of a thermal circulation, which affects the life of animals. 



