HISTORY OP THE CEETACEOUS FLINTS. 46 



ference in the relative percentages of carbonate of lime and silica 

 would be observable as could warrant us in pronouncing the two 

 formations to be lithologically distinct. 



2. Were it possible to compare a given quantity of the recent 

 calcareous mud with a like quantity of the same material when 

 finally converted into a calcareous rock, the difference in the per- 

 centages of carbonate of lime and silica would correspond closely 

 with that now observable between the Chalk and the recent mud. 



3. "Were it possible to compare the percentages in, say, a hundi^cd 

 cubic feet of recent calcareous mud with those in a like cubic 

 volume of flint-bearing chalk, they would be found to correspond, 

 due allowance being made in each case for minor discrepancies 

 resulting either from secular or local changes which affect the 

 supply of material or the due increase of animal life*. 



Before proceeding, however, to apply these propositions to the 

 case of the flints it is essential that I should not only place beyond 

 doubt the adequacy of the sources whence are obtained the vast 

 quantities of protoplasm t and silica required for the production of 

 the flint-formation, but should furnish satisfactory reasons for 

 entering into much more detail on this portion of my subject than 

 would under other circumstances be admissible. These reasons 

 shall now be briefly stated. 



I am prepared to prove that the main source of the protoplasm, 

 as well as of the silica, is to be found in the substance described, in 

 1868, by Prof. Huxley, under the name of " BatJujhlus,'' and that 

 this substance is neither more nor less than sponge-protoplasm 

 derived from the deep-sea sponges which have been found swarming 

 in certain regions of the ocean, and will, I believe, be eventually 

 found to have constituted, in past geological periods, an all-important 

 factor in the production, from organic materials, of probably all cal- 

 careous and siliceous rocks formed at the bottom of the sea. 



In the ' Quarterly Journal of Microscopical Science ' for Dec. 

 1868, Prof. Huxley described Bathyhius. 



In the succeeding number of that journal + I endeavoured to 

 show that Bathyhius, together with the " Coccoliths," which were 

 regarded by Prof. Huxlej^ as forming part and parcel of its structure, 

 do not represent any independent living type of being, that they 

 stand in no physiological, but only in an accidental and purely 

 mechanical relation to each other, and that analogy and the bulk 

 of direct evidence are in favour of the supposition that this widely 

 distributed protoplasmic matter is the product and not the source of 

 the vital forces already in operation at the sea-bed. 



In order to render intelligible the conclusion I arrived at with 



* As a matter of fact, such discrepancies are at the present day encountered 

 in the calcareous mud obtained from different regions, and even at different 

 points in the same geographical area, the causes inducing them being, in all 

 probability, of the kind suggested. 



t I have used this term throughout the present inquiry as being less technical 

 than sarcode, and less specialized than albumen. 



X " On the Vital Functions of the Deep-Sea Protozoa," by G. C. Wallicb, M.D. 

 Quart. Journ. Micr. Science for January 1860. 



