202 THE DAWN OF LIFE. 



school, and maintained that the beds of various silicates found 

 in the crystalline schists are original deposits, and not formed 

 by an epigenic process (Geognosie, ii., 65, 154, and Bull. 

 Soc. Oeol. de France, 2, xviii., 678). This conclusion of 

 Naumann's I have attempted to explain and support by 

 numerous facts and observations, which have led me to the 

 hypothesis in question. Gumbel, who accepts Naumann's 

 view, sustains my hypothesis of the origin of these rocks in a 

 most emphatic manner,* and Credner, in discussing the genesis 

 of the Eozoic rocks, has most ably defended it.f So much 

 for my theoretical views so contemptuously denounced by 

 Messrs. King and Rowney, which are nevertheless unhesita- 

 tingly adopted by the two geologists of the time who have 

 made the most special studies of the rocks in question, 

 Gumbel in Germany, and Credner in North America. 



" It would be a thankless task to follow Messrs. King and 

 Rowney through their long paper, which abounds in state- 

 ments as unsound as those I have just exposed, but I cannot 

 conclude without calling attention to one misconception of 

 theirs as to my view of the origin of limestones. They quote 

 Professor Hull's remark to the effect that the researches of 

 the Canadian geologists and others have shown that the oldest 

 known limestones of the world owe their origin to Eozoon, and 

 remark that the existence of great limestone beds in the Eozoic 

 rocks seems to have influenced Lyell, Earn say, and others in 

 admitting the received view of Eozoon. Were there no other 

 conceivable source of limestones than Eozoon or similar cal- 

 careous skeletons, one might suppose that the presence of such 

 rocks in the Laurentian system could have thus influenced 

 these distinguished geologists, but there are found beneath the 

 Eozoon horizon two great formations of limestone in which 

 this fossil has never been detected. When found, indeed, it 

 owes its conservation in a readily recognisable form to the 



* Proe. Royal Bavarian Acad. for 1866, translated in Can. 

 Naturalist, iii., 81. 



t Die Gliederung der Eozoischen Formations gruppe Nord.- 

 Amerikas, a Thesis defended before the University of Leipzig, 

 March 15, 1869, by Dr. Hermann Credner. Halle, 1869, p. 53. 



