26o RELICS OF PRIMEVAL LIFE 



than that old fancy of the Egyptians, which de- 

 rived animals from the fertile mud of the Nile. 



If we fail to learn anything of the origin of 

 Eozoon, and if its life-processes are just as inscrut- 

 able as those of higher creatures, we can at least 

 inquire as to its history in geological time. In 

 this respect we find in the first place that the 

 Protozoa have not had a monopoly in their pro- 

 fession of accumulators of calcareous rock. Origin- 

 ated by Eozoon in the old Laurentian time, this 

 process has been proceeding throughout the geo- 

 logical 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 con- 

 tinent-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 ob- 

 served in connection with this, that as the work 

 of the Foraminifers has thus been assumed by 



