TJNIVEBSALITY OF ANIMAL LIFE. 351 



say, the horizon of life, has been expanded before our eyes. 

 " Not only in the polar regions is there an uninterrupted 

 development of active microscopic life, where larger animals 

 can no longer exist, but we find that the microscopic animals 

 collected in the Antarctic expedition of Captain James Ross, 

 exhibit a remarkable abundance of unknown and often most 

 beautiful forms. Even in the residuum obtained from the melted 

 ice, swimming about in round fragments, in the latitude of 

 70 10', there were found upwards of fifty species of siliceous- 

 shelled polygastria and coscinodiscaB with their green ovaries, 

 and therefore living and able to resist the extreme severity of 

 the cold. In the Gulf of Erebus, sixty-eight siliceous- shelled 

 polygastria and phytolitharia, and only one calcareous-shelled 

 polythalamia, were brought up by lead sunk to a depth of 

 from 1242 to 1620 feet." 



The greater number of the oceanic microscopic forms 

 hitherto discovered have been siliceous-shelled, although the 

 analysis of sea water does not yield silica as the main con- 

 stituent, and it can only be imagined to exist in it in a state of 

 suspension. It is not only at particular points in inland seas, 

 or in the vicinity of the land, that the ocean is densely 

 inhabited by living atoms, invisible to the naked eye, but 

 samples of water taken up by Schayer on his return from 

 Van Diemen's Land (south of the Cape of Good Hope, in 57 

 latitude, and under the tropics in the Atlantic) show that 

 the ocean in its ordinary condition, without any apparent 

 discoloration, contains numerous microscopic moving organ- 

 isms, which bear no resemblance to the swimming frag- 

 mentary siliceous filaments of the genus chastoceros, similar 

 to the oscillatoriaB so common in our fresh waters. Some 

 few polygastria winch have been found mixed with sand and 

 excrements of penguins in Cockburn Island appear to be 

 spread over the whole earth, whilst others seem to be peculiar 

 to the polar regions.* 



* See Ehrenberg's treatise Ueber das kleinste Lcben im Ocean, read 

 before the Academy of Science at Berlin, on the 9th of May, 1844. 



[Dr. J. Hooker found Diatomaceas in countless numbers between the 

 parallels of 60 and 80 south, where they gave a colour to the sea, and 

 also to the icebergs floating in it. The death of these bodies in the 

 South Arctic Ocean is producing a sub-marine deposit, consisting 

 entirely of the siliceous particles of which the skeletons of these 

 vegetables are composed. This deposit exists on the shores of Victoria 



