CHALK MAKERS, OR FORAMINIFERA. 57 



that this supplied sufficient material to mount one 

 hundred and ninety microscopical slides, of equal 

 character, indeed the whole of that number were 

 prepared, and compared. Each of these slides was 

 estimated to contain one thousand shells, based upon 

 the actual counting of two or three. So that, by 

 calculation, it could be shown that in one ounce of 

 chalk there were 400,000 shells. 



Afterwards, and for greater security, another ounce 

 of chalk was washed, even more carefully, and the 

 calculation then showed upwards of half a million of 

 entire shells, without reckoning the fragments which 

 had been washed away, or probably the thousands 

 that had been decanted off with the water in forty 

 or fifty washings. Hence, it is evident that the 

 maximum is not reached when it is affirmed that, at 

 least, half a million of the shells of Foraminifera were 

 contained in each ounce of chalk from that pit. The 

 lump of chalk procured as the basis of these experi- 

 ments weighed sixteen pounds, or 256 ounces, and 

 consequently contained the shells of 128 millions of 

 Foraminifera. Such a number is easy to name, but 

 not so easy to imagine, a number which would 

 occupy a person ten years to count, even if he could 

 continue to count sixty per minute, for twelve hours 

 daily. 



Professor Ehrenberg, the celebrated German micro- 

 scopist, calculated that there are one million and 



