PHYSICAL CONDITIONS OF THE DEEP SEA. 471 



the calcium carbonate shells of animals as they sink to the bot- 

 tom, and during the long and very slow journey from the surface 

 to the bottom of the deepest seas these shells are completely dis- 

 solved. The first to be dissolved would be the thin, delicate shells 

 of the pteropods and heteropods, for besides the fact that they 

 present a wider surface to the solvent action of the water they are 

 probably influenced more by tide and currents, sink more slowly 

 and erratically, and thus have a longer journey to perform. Then 

 the smaller but more solid and compact shells of the foraminifera 

 are dissolved, and lastly, in the deepest water only the siliceous 

 skeletons of the radiolariaand diatoms are able to reach their last 

 resting place at the bottom of the ocean. 



These four oozes then are characteristic of the floor of the deep 

 oceans. In the proximity of land and in inland seas where deep 

 water occurs, other muds are found differing from one another in 

 accordance with the character of the coasts in their vicinity. 



One more character of the deep-sea region must be referred to, 

 and that is the absence of vegetable life. It has not been deter- 

 mined yet with any degree of accuracy where we are to place the 

 limit of vegetable life, but it seems probable that below a hundred 

 fathoms no organisms, excepting a few parasitic fungi, are to be 

 found that can be included in the vegetable kingdom. While then 

 the researches of recent times have proved beyond a doubt that 

 there is no depth of the ocean that can be called azoic, they have 

 but confirmed the perfectly just beliefs of the older naturalists 

 that there is a limit where vegetable life becomes extinct. It is 

 not difiicult to see the reason for this. All plants, except a few 

 parasites and saprophytes, are dependent upon the influence of 

 direct sunlight, and as it has been shown above that the sunlight 

 can not j^enetrate more than a few hundred fathoms of sea water, 

 it is impossible for plants to live below that depth. 



Noticing the proceedings of the recent meeting of the British Association at 

 Nottingham, the London Spectator remarks upon ''a singular deficiency in those 

 careful descriptions of the precise position of any science which have so frequently 

 wakened up ordinary men to careful thought." There is a popular side to the 

 association's work which is not less important than the one hy which it seeks to 

 advance science. The aim of that side is "to arouse such general interest in sci- 

 ence that the minds which are fitted for such study will be inclined to devote 

 themselves to it. To obtain the ablest in any pursuit we need a vast reservoir of 

 men who are more or less interested in it. You can not have jour Napoleon of 

 science without an army to draw him from, and the work of increasing the area 

 of recruiting is not unworthy a great association. Of course, ' interesting papers ' 

 often add little to positive science; but then, neither do music and banners and 

 tine uniforms add to military force. But they bring recruits, without which such 

 force remains latent and useless.'' 



