276 M. Otto Hahn on Eozoon canaclense. 



In these and a great number of serpentine limestones there 

 were everywhere the alternating layers of serpentine and lime- 

 stone, but nowhere the so-called canal- systems of the Canadian 

 Eozoon. 



Upon this, however, I lay no great weight after the results 

 subsequently obtained. Where these canal-systems do not 

 occur, there is, as I must mention at once, no trace of proba- 

 bility for an organic structure. 



According to a communication from King and Rowney, 

 ophicalcites occur even in the Lias of Scotland. 



From the preceding statements it follows tliat even with 

 respect to the question whether £'o20c»?i-structures exist, we 

 must carefully and in the iirst place ascertain quite clearly 

 what are the essential characters of Eozoon. If the investi- 

 gator lays especial stress upon the chambers or alternating- 

 layers of serpentine and limestone, he will iind£'o^oon-structures 

 wherever serpentine occurs. I have such specimens out of 

 mineral deposits. I have a specimen of serpentine limestone in 

 which the two layers appear exactly in the same form as in the 

 Canadian specimens, but are 2 centims. instead of 1*5 millim. 

 in thickness. 



I have, in the first place, to refer to the formation of ser- 

 pentine. 



Serpentine is not an original, but a metamorphic rock. As 

 is well known, there is no rock which is so certainly the result of 

 metamorphism and can be derived from so many minerals as 

 serpentine ; Gustav Rose has shown that it may originate from 

 augite, hornblende, pyrope, and spinel. It probably originates 

 in the greatest masses from olivine, and, indeed, by the access 

 of water. But everywhere it occurs in association with lime- 

 stone ; and so the alternate layers of the two substances cannot 

 be in the least surprising. 



I have investigated an immense number of serpentines, and 

 always found that they are products of metamorphism. Take 

 the Snarum pseudomorphs after olivine, in the interpretation 

 of which Prof. Quenstedt first proved his mastership. In these, 

 olivine grains, still undecomposed, lie in the olivine crystal, 

 which is now serpentine. The crystalline form has persisted ; 

 the olivine has been converted by access of water into ser- 

 pentine. 



The basalts of the Swabian Alb (especially those of Eisen- 

 riittel) display in every hand-specimen the distinct picture of 

 the serpentinization of olivine. The Karfenbiihl, near Det- 

 tingen, consists for the most part of such serpentine. In the 

 Canadian serpentine limestone also olivine grains are to be 

 detected with fragments of limestone in the serpentine. By 



