HISTOBY OF THE CRETACEOUS FLINTS. 77 



water holding it in solution, under the chemical treatment described ; 

 but, with the greatest respect for the opinion of so able and con- 

 scientious an observer as Mr. Buchanan has proved himself to be, 

 I am quite unable to accept his explanation that amorphous sulphate 

 of lime and the glairy matter pervading and overlying the mud in 

 such vast abundance and so universally, which was described as 

 being actually alive and sticking together in lumps, as if white of 

 egg were mixed with it, which, moreover, proved under the micro- 

 scope to be " living sarcode," are, or can be, one and the same thing. 



Fortunately the subjoined data relating to twenty samples of 

 bottom obtained on board the ' Challenger ' while traversing one of 

 the most important and typical sections of the Atlantic, stretching 

 across from Teneriffe to the entrance of the Caribbean Sea, furnish 

 a complete verification of the opinion just expressed by me. Ac- 

 cording to analyses by Mr. Brazier*, the average quantity of sul- 

 phate of lime present in seven samples of " globigerine ooze," and 

 twelve samples of " red clay," was only a fraction over 1 per cent., 

 a quantity altogether insignificant, and obviously quite inadequate 

 to account for the presence of such enormous masses of glairy proto- 

 plasmic matter as have been described, on the assumption that it is 

 not true protoplasm, but merely a flocculent substance, derived, by 

 an artificial chemical method, and only in the presence of alcohol, 

 from sulphate of limef. 



It is deserving of mention, in relation to the sulphate-of-lime ques- 

 tion, that in none of the published analyses of the deep-sea water 

 or mud obtained during the cruises of the ' Porcupine ' and ' Light- 

 ning,' in the years 1868-1870, have I been able to find any notice 

 of that substance. This fact is of itself evidence, therefore, that 

 no very material quantity of sulphate of lime was then met 

 with ; and putting all these facts together, it may, I submit, be 

 safely concluded that not only once (as in the 2435-fathom dredging 

 so graphically described by Sir Wyville Thomson), but on many other 

 equally important occasions, the dredge must have plunged head- 

 long into one of the ubiquitous sponge-beds — the glairy mass like 

 white of egg^ the multitudes of spicules distributed like hair in 

 mortar throughout the mud, and the apparent residuum of contractile 

 power in the glairy substance, said to have lingered in it even after 

 it had been treated with alcohol, all furnishing distinct and un- 

 equivocal testimony to the fact that the substance in question was 

 no allotropic condition of a salt of lime, but veritable sponge-proto- 

 plasm, existing under conditions, of all others, pre-eminently cal- 

 culated to foster gigantic development. 



In a very remarkable paper published in the ' Quarterly Journal 

 of the Geological Society ' in 1849, the late Mr. Bowerbank, while 



* ' The Atlantic,' vol. ii. Appendix A, p. SG9. 



t As a matter of fact, twenty examples of mud were analyzed by Mr. Brazier ; 

 but as the twentieth was from the conjparatively shallow depth of 450 fathoms, 

 I thought it expedient not to include it in the estimated percentiges. The per- 

 centage of sulphate of lime in it was, however, exactly 1 per cent. The general 

 average is therefore in no wise vitiated. 



