182 Dr. Wallich on the Origin of the 



occur in deep water, and that the forms taken alive at tlie 

 immediate surface of the ocean in some latitudes are sufficiently 

 distinct to prove that the same species do not occur at the 

 surface and at the bottom without undergoing marked modifi- 

 cation. On the other hand, there is reason to believe that 

 some of the siliceous organisms met with in a living condition 

 at the surface of the open ocean cannot live at any great 

 depth, and that,y/'om some peculiarity in molecular constitution^ 

 the siliceous portion of their structure yields to the solvent 

 power of the water. Thus the Acanthometrina, a small group 

 of organisms with siliceous frameworks of extreme symmetry 

 and of such characteristic shape as to be readily distinguish- 

 able, occur in tolerable profusion in tropical and subtropical 

 latitudes ; but^ strange to say, not a trace of their siliceous re- 

 mains is to he found either in recent or fossil oceanic deposits ''^ 

 {ibid. pp. 126, 127). 



I have still in my possession unmounted and mounted mate- 

 rial obtained by me in 1857 from the surface of the Indian 

 Ocean, and Southern and Mid-Atlantic Ocean, containing 

 specimens, in considerable numbers, of Acanthometrce, Poly- 

 cystina, Dictyochidce, Diatomacoiy and Sphoirozoidce — the 

 mounted specimens in Canada balsam, the crude material in 

 dilute alcohol. In both cases, the Acanthometrce, and some of 

 the very delicate oceanic Diatomacw, with the thin-shelled 

 SphoirozoidcBj were the first to show signs of solution, about 

 ten years after they were obtained. In twenty years most of 

 these had vanished as visible structures, but the fluffy resi- 

 duum of their sarcodic bodies remained. Now some of the 

 more solidly built forms are beginning to yield, and probably 

 will do so in the course of a few scores of years, which, it is 

 almost needless to say, is but a moment in comparison with 

 the periods involved in any of the great chemical or molecular 

 changes brought about in Nature. But, surely, no fact could 

 be more clearly indicative of the potency residing in proto- 

 plasm than the one just furnished, these minute siliceous struc- 

 tures having, undoubtedly, given way under the powerful 

 colloidal properties of what was once their own body-sub- 

 stance. 



What, then, do these facts prove ? First and foremost, they 

 prove, by the presence of forms belonging to genera which 

 invariably live along coast-lines*, and possessing stalk or 

 cushion-like processes whereby they anchor themselves to rocks 

 or shells, or alga3 at the bottom of the sea, that the deposit 

 in which their remains occur could not have been formed at 

 any great distance from land, and that they were, in all pro- 

 * At depths probably never exceeding oO or 60 fathoms. 



