Botanical Society of Edinburgh. 155 



deep blood-red spot, beautifully soft at the edges ; grind a little 

 farther, and it assumes the appearance recognized as the resiiioid 

 cell ; a little more grinding, and the spore-case makes its appearance ; 

 still grind on, the process will be found to be as fertile of form as the 

 frost is on the window-pane, or the burning embers of the fire to a 

 musing fancy ; and when the section is reduced to the last degree of 

 thinness, the shallowest of all peep through. These are the yellow 

 rings, with their dark centres, on which I shall venture a few obser- 

 vations suggestive of their origin. 



" A painting of a transverse section, executed by Dr. Adams of 

 Glasgow, and shown by Professor Bennett to the Royal Society, re- 

 presents the rings as if they were all in the level, and of a uniform 

 colour. This has no doubt been in some measure the cause of their 

 having been mistaken for the ends of tubes. Nature shows them dif- 

 ferent. Some are distinct and bright yellow, while thin as the sec- 

 tion is when they come into view ; others are still obscured by a layer 

 of dark matter, and have a bistre-brown colour. Mr. Quekett admits 

 this to be the case ; it is therefore a matter of astonishment that, 

 with such a high and well-earned reputation for acute observation, 

 he, at the same time, describes them as transverse sections of thick- 

 walled cells or woody fibre. 



" In the longitudinal section these bodies present their edges, are 

 seen strewed all over the sections, and sometimes assume the appear- 

 ance of an interrupted yellow line, and individuals now show their 

 dark centres flattened. 



" The dark bodies in the centres of the ring seem to me to be car- 

 bonized spores. They have the characteristic outline of a cell, are 

 some of them still quite spherical, and in Professor Balfour's speci- 

 men of Wigan Cannel Coal, where the edge of the section is reduced 

 to a rag, some of them are partially divested of the encircling yellow, 

 when the spore is seen to project into the empty field. The remains 

 of some are also seen as black circular lines, sticking in the varnish 

 with which the specimen had been fixed to the glass. 



" The transparent yellow I suppose to have been pressed out in 

 the process of carbonization, or perhaps gathered round them as a 

 pool of water encircles a stone on the sea-beach long after the retiring 

 tide has left all else dry. 



" In short, living vegetable matter may with tolerable accuracy be 

 considered as a semi-opake substance. The process of carbonization 

 by which it is changed into coal, seems to separate the structural 

 from the non-structural, the opake from the transparent, and as the 

 former is compressed and blackened, the latter is insinuated be- 

 tween the layers, and into every minute fissure and crevice left vacant 

 around the more resistent particles of the carbonaceous mass ; while 

 decomposed portions are being constantly carried to the surface of 

 the earth, by capillary attraction, there to be thrown off into the 

 atmosphere or taken up by the minute spongioles and rootlets of the 

 existing vegetation." 



3. " On the effects of the recent frosts on vegetation, in different 

 parts of the country," by Mr. M'Nab. 



