OSBORNE, ON VEGETABLE GROWTHS. 87 



stated that many of the grains of Greensand accompanying 

 the well-defined casts are of wholly unrecognisable forms, 

 having merely a ronnded, cracked, lobed, or even coproiitic 

 appearance. Certainly many of these masses, which often 

 compose whole strata, were not formed either in the cavities 

 of Polythalamia or Mollnsks. The fact, however, being esta- 

 blished beyond a donbt, that Greensand does form casts in 

 the cavities of various organic bodies, there is a great pro- 

 bability that all the masses of this substance, however 

 irregular, were formed in connection with organic bodies ; 

 and that the chemical changes accompanying the decay of 

 the organic matter have been essentially connected with the 

 deposits in the cavities, of green and red silicates of iron, and 

 of nearly piu'c silica. It is a curious fact in this connection, 

 that the siliceous organisms, such as the Diatomaceae, Polycis- 

 tineae, and Spongiolites, which accompany the Polythalamia 

 in the Gulf Stream, do not appear to have any influence in 

 the formation of casts. 



The discovery by Professor Ehrenberg, of the connection 

 between organic bodies and the formation of Greensand, is 

 one of very great interest, and is one of the many instances 

 which he has given to prove the extensive agency of the 

 minutest beings in producing geological changes. 



Further Observations on Vegetable Growth. 

 By the Hon. and Rev. Sidney Godolphin Osborne. 



It may interest the readers of the ' Joui-nal ' to know that 

 fiu'ther observation has given me a deeper insight into the 

 structure of the wheat plant in the earliest stage of its 

 growth. I find there is a " circulation " in every one of the 

 long suckers put forth from the roots ; it may be seen very 

 plainly under a power of 800. Although I can trace it with 

 ease along the outer edge of each sucker, running from the 

 root towards the blunt point, I cannot trace any current re- 

 turning towards the root. 



In the case of the spiral fibre in the early plumule, I now 

 find it to have in every case its own investment ; that, in fact, 

 it is within a tube of very thin cellular texture. By careful 

 management of the light, lines running vertically the whole 

 length of this tube can be seen; I presume these to be the 

 outlines of a fine wall of cells, of which tliis tube is formed. 

 The coils of fibre, if attached at all to this tube, are only 

 partially so, as I have succeeded by pressure in extending a 



