- Botanical Society of Edinburgh. 219 



of the seeds of Pistia (Ueber Pistia, Berl. 1853, plate 1. f. C.D.E), 

 where the many secondary rootlets, or branches of the neorhiza, 

 force their way through the epirhizal covering of the main root, ex- 

 tending it as a coleorhiza, in the form of a long cj'lindrical tube, 

 which at length breaks away, leaving a long sheath in the form of a 

 thimble, covering the extremity of each growing rootlet, and which 

 probably thus performs the functions of a spongiole. 



BOTANICAL SOCIETY OF EDINBURGH. 



Thursday, 12th July 1855. — Professor Balfour, President, in 

 the Chair. 



The follomng papers were read, viz. — 



1 . " On the Introduction of the Cinchona Tree into India." By 

 Thomas Anderson, M.D., H.E.I.C.S. 



The author gave an account of the peculiar character of the 

 country inhabited by the Cinchona tree, and showed that similar 

 districts existed in India where this valuable tree may be successfully 

 growu. He also showed, by the great quantity of the bark that is 

 used, that much profit must result to the cultivators. 



2. " On the presence of DiatomaceEe, Phytolitharia, and Sponge 

 Spicules, in Soils which support Vegetation." By William Gregory, 

 M.D., F.R.S.E., Professor of Chemistry. 



Ehrenberg, in his late work, ' Mikrogeologie,' has stated that in 

 specimens of soils from all parts of the world, he has found many 

 microscopic organisms ; he divides these into Siliceous and Calcareous, 

 the former including Biatomacece, PJajtolitharia, and Pohjcystina, 

 as well as Sponge spicules, the latter minute INIollusks and other 

 shells. The present observations are confined to the siliceous organ- 

 isms, and among these, chiefly to the Diatomacete, with Phytolitharia 

 and Sponge spicules, the soils examined being such as are connected 

 with fresh water, in which the Polycystina do not occur. 



Many of Ehrenberg' s observations were made on the small por- 

 tions of soil found adhering to dried plants in herbaria, and I requested 

 Professor Balfour to supply me with such portions of soil. By his 

 kindness I obtained upwards of sixty such specimens, almost all of 

 which were of very small bulk, on an average uot exceeding that of 

 a pinch of snuflF, and sometimes less. Of these a certain number 

 consisted chiefly of earth, with some half-decayed vegetable matter, 

 and many contained hardly anything but decaying vegetable matter, 

 with a 7nere trace of earth. Of course, the latter are not fair speci- 

 mens of soil; but I have subjected all to the same treatment, namely 

 boiling with nitro-muriatic acid, washing, straining through gauze, 

 and examining the fine insoluble residue. This, of course, contained 

 all the siliceous matter present, but it also contained much organic 

 matter, of a brown or red colour, insoluble in acids, which, if neces- 

 sary, might be destroyed by ignition, when it would leave a trifling 

 ash. 



15* 



