M. Otto Halm on Eozoon canadense. 277 



this, of course, the filling of the chambers would immediately 

 be got rid of as an impossibility ; but it might be objected that 

 here the olivine grains are not quite certain, and the serpentine 

 bands, which are vermiform in their section, cannot be so easily 

 explained away. 



But at the conclusion of my investigation I was so fortunate 

 as to obtain two specimens of serpentine limestone which re- 

 move all doubts. Their derivation is unknown to me ; but this 

 does not affect the matter ; at any rate, they are not from 

 Canada. 



Tiiese specimens show in their interior exactly the same 

 serpentine layers as the Canadian ones, and in section exactly 

 the same chambers ; but in the middle of the chambers are 

 the olivine grains, which still polarize splendidly (red and 

 green). In the rock, where the decomposition has not advanced 

 so far, there are still round, oval, and angular fragments, and, 

 finally, I found the cleavage-planes with the angle of olivine. 



That olivine here also is the parent of serpentine is induT 

 bitable ; but at the same time it is shown how the decomposi- 

 tion of the olivine took place. The olivine changed from 

 without into a gelatinous mass. This, as is well-known, 

 happens in areas ; and hence, as chrysotile-threads form at 

 the limits of the areas, the serpentine has afterwards the 

 appearance of chambers. The decomposition may thus be 

 followed piece by piece, and through all stages up to the struc- 

 ture of the Canadian specimens. The gelatinous mass no 

 longer polarizes ; but the newly formed serpentine mass pola- 

 rizes in the same fashion as all aggregated rocks ; a new 

 crystal-formation has commenced. 



Thus in these two specimens the serpentine structure may be 

 traced in accordance with the form that it took on in corre- 

 spondence with the action of the decomposing water, from the 

 imbedded and still perfectly preserved olivine crystal with 

 distinct cleavage-planes to the (formerly fluid) serpentine mass. 

 Conceive the olivine crystals gradually converted into a gela- 

 tinous matter. The latter must have deposited itself iiniformly 

 in the calcareous mass, which was also still soft, and conse- 

 quently must have become round. Now the slightest vertical 

 pressure sufficed to give the gelatinous spheres a cylindrical or 

 lenticular form ; their section will always be a line, like that 

 of the Canadian Eozoon-xoc\.. The intermediate passages 

 also occur. Further, everywhere on the serpentine, in places 

 at the points of contact with the limestone, there is the 

 " film " or asbestos-layer, i. e. a crystallized layer with 

 needles. 



In these specimens, therefore, we have the proof that the 



