I6O WHAT MAY BE LEARNED FROM EOZOON 



the Protozoa have not had a monopoly in their profession of 

 accumulators of calcareous rock. 



Originated by Eozoon in the old Laurentian time, this pro- 

 cess has been proceeding throughout the geological ages ; and 

 while Protozoa, equally simple with the great prototype of the 

 race, have been and are continuing its function, and producing 

 new limestones in every geological period, and so adding to 

 the volume of the successive formations, new workers of higher 

 grades have been introduced, capable of enjoying higher forms 

 of animal activity, and equally of labouring at the great task 

 of continent building ; of existing, too, in seas less rich in 

 mineral substances than those of the Eozoic time, and for that 

 very reason better suited to higher and more skilled artists. It 

 is to be observed in connection with this, that as the work of 

 the Foraminifers has thus been assumed by others, their size 

 and importance have diminished, and the larger forms of 

 more recent times have some of them been fain to build up 

 their hard parts of cemented sand instead of limestone. 



When the marvellous results of recent deep-sea dredgings 

 were first made known, and it was found that chalky foram- 

 iniferal earth is yet accumulating in the Atlantic, with sponges 

 and sea urchins, resembling in many respects those whose 

 remains exist in the chalk, the fact was expressed by the state- 

 ment that we still live in the chalk period. Thus stated the 

 conclusion is scarcely correct. We do not live in the chalk 

 period, but the conditions of the chalk period still exist in the 

 deeper portions of the sea. We may say more than this. To 

 some extent the conditions of the Laurentian period still exist 

 in the sea, except in so far as they have been removed by the 

 action of the Foraminifera and other limestone builders. To 

 those who can realize the enormous lapse of time involved in 

 the geological history of the earth, this conveys an impression 

 almost of eternity in the existence of this oldest of all the 

 families of the animal kingdom. 



