[ 238 i 



Selected IRotee from tbe Socictij'e 

 IRote^Boohe* 



GEOLOGICAL. 



Carb. Limestone Nodule.— This slide may be viewed either by 

 hand-glass or by J-inch o.g., and either way it will tell its tale. 

 Describing the reverse from the hand-glass view, there are at least 

 a dozen of what are called Stigmarian rootlets. The medulla is 

 in each rootlet, but not in the centre of any. These are bundles 

 of firm scaliform vessels, that had their origin in the vascular 

 cylinder of the root. In some of the rootlets they are transverse, 

 in others tongitudinal. Outside of this medulla was a mass of 

 cellular tissue very delicate, and therefore rarely preserved in the 

 nodules; outside of the central or sub-central mass, was a cortical 

 mass of denser cellular tissue. This is preserved more or less in 

 this specimen, and constitutes the bark, if I may " forge " a term, 

 of the Stigmarian rootlet. The dark masses in the centre are 

 remains of ferns, the one or more species of the Rachiopttris tribe 

 of Williamson. Transverse section of stem, with its beautiful 

 vascular bundles enclosed in cellular bark, and all about the dark 

 mass of the slide, may be seen various fragments of leaves, stems, 

 and a spore or two of some species of the Rachiopteris tribe. 

 Altogether the fragments on the slide amount to considerably over 

 I GO, so that in viewing this we see, not the whole certainly, but a 

 superficial inch of a carboniferous forest, and as such it would be 

 best to consider it. There is one caution, however ; the more 

 beautiful and delicate tissues of the Stigmaria are lost. Carnithers 

 says that he has never once seen this tissue in all the material that 

 has passed through his hand. I believe Williamson somewhere 

 says the same, and although I have examined over 2,000 speci- 

 mens, I have only seen it faintly and delicately preserved in one 

 specimen alone, and I am therefore able to say that the tissues 

 which surround the medulla in the rootlet are fine, delicate cel- 

 lular tissues, similar in character to the outer bark, but with cell- 

 walls of most remarkable fineness. In one of the specimens a 

 small portion of this tissue is preserved. 



G. R. Vine. 



