of the so-called 'Crystalloids' of the Chalk. 195 



in some natural deposits — and pointed so clearly to their having 

 been derived from small hollow spheres, that I felt persuaded 

 that such was their origin. The small cells of Foraminifera 

 occurring in the chalk being just the size and thickness that 

 would agree with this supposition, I endeavoured for a long time 

 to make out that the ovoid bodies were in some way or other 

 derived from them. I thought that, when decomposition took 

 place, perhaps the calcareous matter might have re-arranged 

 itself into more or less circular concretions whilst still in the form 

 of the cells of Foraminifera, and thus, on further decay, they 

 might have broken up into ovoid bodies of the form described 

 above. I sought diligently for proof of this, but in vain, though 

 I convinced myself that a very considerable part of the minute 

 particles of the chalk was certainly derived from the decomposed 

 tissue of Foraminifera. Notwithstanding this, I still adhered to 

 the supposition of their having originated from organic spheres, 

 and endeavoured to clear up the difficulty by studying recent 

 deposits. Some eight or nine years ago, when examining mud 

 from our own shores, I found one single body which was ob- 

 viously similar to those in the chalk, both in form and optical 

 characters, but was unable to make out its true nature. 



In 1858 appeared Prof. Huxley's Report on the Deep-Sea 

 Soundings in the Atlantic, in which, at p. 64, he says that in all 

 the specimens, from depths varying between 1700 and 2400 fa- 

 thoms, he had found "a multitude of very curious rounded bodies, 

 to all appearance consisting of several concentric layers sur- 

 rounding a minute clear centre, and looking at first sight some- 

 what like single cells of the plant Protococcus ; as these bodies, 

 however, are rapidly and completely dissolved by dilute acids, 

 they cannot be organic, and I will for convenience' sake simply 

 call them Coccoliths." 



Still nourishing the conviction that ovoid bodies like those in 

 chalk would be found in deep-sea deposits, at my request I was 

 kindly furnished by Prof. Huxley with some of the Atlantic mud 

 from a depth of 2230 fathoms. I was at that time as ignorant 

 of what he had written on the subject as he was of my object, 

 and of the connexion between the bodies he had described and 

 the chalk. Directly I examined it with the microscope, I per- 

 ceived that my long-cherished belief was true, and that this 

 deep-ocean mud would completely explain the peculiar charac- 

 ters of our Chalk formations. Nor was this all ; for on the 27th 

 of August of last year (1860) I found that, as I had predicted 

 several years before, the ovoid bodies were really derived from 

 small hollow spheres, on which they occur, separated from each 

 other, at definite intervals. I therefore read a short paper on 

 the subject at the meeting of the Sheffield Literary and Philo- 



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