1849.] BOWERBANK ON A SILICEOUS ZOOPHYTE. 325 



the interior of the earth ; but as regards the supply of silex in the 

 production of fossils, and in its appropriation by living organisms, I 

 believe them to have infinitely less to do with these phsenomena than 

 has hitherto been supposed. 



Modern chemistry has shed much light upon this subject, and has 

 show^n us that silex is very much more soluble than was formerly 

 supposed. It has taught us that most sandstones contain, mixed 

 with them, silicates with alkaline bases ; and that in the decomposition 

 of granite, porphyry, and other similar rocks, vast quantities of soluble 

 silicates are liberated and poured into the ocean in solution ; and 

 thus, although in unappreciable quantities, silex must necessarily exist 

 in sea-water. 



For many years chemistry failed to demonstrate the existence of 

 iodine in sea-water ; but as the science advanced, it was found by 

 Dr. G. Schweitzer, in his analysis of sea-water from the British 

 Channel, published in the 'Philosophical Magazine' for 1839*, 

 that it did exist in it, although in so minute a degree as to form 

 not more than one-millionth of its bulk in a given quantity ; and 

 this fact, from the peculiar qualities of the substance, was readily 

 demonstrable. But the same peculiar qualities do not exist in silex, 

 and its presence, although probably in greater proportional quantities, 

 cannot be rendered apparent by any chemical test that is at present 

 known to science ; but that it does exist in sea-water is evident from 

 the vast quantities of siliceous infusorial animalcules, which can 

 derive, from no other imaginable source, the material with which 

 they construct their cells. These minute and interesting creatures 

 exist by myriads in the ocean in all quarters of the globe, forming no 

 inconsiderable portion of the food of conchiferous moUusks, whence 

 they are conveyed into the stomachs of fishes, which becoming in 

 turn the prey of sea-birds, are thence conveyed by them and deposited 

 in their excrements on rocks and islands, where amidst the guano 

 they are found in a beautiful and perfect state of preservation. Vast 

 quantities of them are also found attached to fuci and zoophytes, 

 and I have them in this condition from the shores of Africa, Australia, 

 Japan, China, and various parts of Europe. It is evident therefore, 

 from the universal prevalence of these minute animals, that silex not 

 only existed in former geological periods in solution in the waters of 

 the ancient seas, but that it also exists in solution in all parts of the 

 seas of the present period ; and however minute and unappreciable 

 the quantity may be to the science of chemistry, it is yet sufficiently 

 large to admit of its continual secretion by the countless myriads of 

 living creatures that need it for their protection and support. 



If it be not so, what becomes of the enormous quantities of soluble 

 silicates that are continually poured into the ocean by the decompo- 

 sition of feldspar, granite, porphyr}^, and other similarly constituted 

 minerals ? Moreover it is a fact satisfactorily established by modern 

 chemists, that these silicates are readily retained in solution by the 



* Vol. XV. p. 51. I have since been informed, that previously to this date 

 iodine had been noticed in sea-water from the Mediterranean bv Balard, and in 

 that of the Baltic bv Pfaff. 



