THE ORIGIN OF LIFE 263 



organisms having silica in their skeletons or cell- 

 walls, and consequently soluble silicates in their 

 juices. The silicious matter contained in these 

 organisms is not wanted by the Foraminifera for 

 their own skeletons, and will therefore be voided by 

 them as an excrementitious matter. In this way, 

 where Foraminifera greatly abound, there may be a 

 large production of soluble silica and silicates, in a 

 condition ready to enter into new and insoluble 

 compounds, and to fill the cavities and pores of dead 

 shells. Thus glauconite and even serpentine may, in 

 a certain sense, be a sort of foraminiferal coprolitic 

 matter or excrement. Of course it is not necessary 

 to suppose that this is the only source of such 

 materials. They may be formed in other ways, 

 and especially by the disintegration of volcanic 

 ashes and lapilli in the sea-bottom ; but I suggest 

 this as at least a possible link of connection. 



Whether or not the conjecture last mentioned has 

 any validity, there is another and most curious bond 

 of connection between oceanic Protozoa and silicious 

 deposits. Professor Wyville Thompson reports from 

 the Challenger soundings, that in certain areas of the 

 South Pacific the ordinary foraminiferal ooze is re- 

 placed by a peculiar red clay, which he attributes to 



