192 THE DAWN OF LIFE. 



In 1864, additional specimens having been obtained by the 

 Survey, slices were submitted to the writer, in which he at 

 once detected a well-marked canal-system, and stated, de- 

 cidedly, his belief that the forms were organic and fora- 

 miniferal. The announcement of this discovery was first made 

 by Sir W. E. Logan, in Silliman's Journal for 1864. So far, 

 the facts obtained and stated related to definite forms mineral- 

 ised by loganite, serpentine, pyroxene, dolomite, and calcite. 

 But before publishing these facts in detail, extensive series of 

 sections of all the Laurentian limestones, and of those of the 

 altered Quebec group of the Green Mountain range, were made, 

 under the direction of Sir "W. E. Logan and Dr. Hunt, and 

 examined microscopically. Specimens were also decalcified by 

 acids, and subjected to chemical examination by Dr. Sterry 

 Hunt. The result was the conviction that the definite lami- 

 nated forms must be organic, and further, that there exist in 

 the Laurentian limestones fragments of such forms retaining 

 their structure, and also other fragments, probably organic, 

 but distinct from Eozoon. These conclusions were submitted 

 to the Geological Society of London, in 1864, after the speci- 

 mens on which they were based had been shown to JDr. Car- 

 penter and Professor T. E. Jones, the former of whom detected 

 in some of the specimens an additional foraminiferal structure 

 that of the tubulation of the proper wall, which I had not 

 been able to make out. Subsequently, in rocks at Tudor, of 

 somewhat later age than those of the Lower Laurentian at 

 Grenville, similar structures were found in limestones not more 

 metamorphic than many of those which retain fossils in the 

 Silurian system. I make this historical statement in order to 

 place the question in its true light, and to show that it relates 

 to the organic origin of certain definite mineral masses, ex- 

 hibiting, not only the external forms of fossils, but also their 

 internal structure. 



In opposition to these facts, and to the careful deductions 

 drawn from them, the authors of the paper under considera- 

 tion maintain that the structures are mineral and crystalline. 

 I believe that in the present state of science such an attempt 

 to return to the doctrine of "plastic-force" as a mode of 



