226 RELICS OF PRIMEVAL LIFE 



and more practically useful researches. On this 

 subject it will not be out of place to quote the 

 remarks which I made in one of my earlier 

 papers on the Laurentian fossils : — 



" This subject opens up several interesting fields 

 of chemical, biological, and geological inquiry. One 

 of these relates to the conclusions stated by Dr. 

 Hunt as to the probable existence of a large 

 amount of carbonic acid in the Laurentian atmo- 

 sphere, and of much carbonate of lime in the seas 

 of that period, and the possible relation of this to 

 the abundance of certain low forms of plants and 

 animals. Another is the comparison already in- 

 stituted by Professor Huxley and Dr. Carpenter, 

 between the conditions of the Laurentian and those 

 of the deeper parts of the modern ocean. Another 

 is the possible occurrence of other forms of animal 

 life than Protozoa, which I have stated in my 

 paper of 1864, after extensive microscopic study 

 of the Laurentian limestones, to be indicated by 

 the occurrence of calcareous fragments, differing in 

 structure from Eozoon, but at present of unknown 

 nature. Another is the effort to bridge over, by 

 further discoveries [similar to those of Cryptozoon 

 and Archeeozoon], the gap now existing between 



