ON THE DIAMOND, OPAL, kc. 
561 
these I conjecture, may be somewhat of an adamantine 
nature. If this should prove to be the case, it would neither 
be surprising nor unexpected, that such trees may secrete 
carbon in the adamantine state, which, on being removed 
from the influence of the living principle of the plant, 
would, by the power of affinity, form into true diamonds, — 
just as the silica secreted from the bamboo takes the form 
of opal, and that from teakwood the characters of horn- 
stone. 
The preceding statement, then, seems to give plausibility 
to the idea, that some sorts of trees may be characterised 
by the power of forming a mineral matter of the nature of 
hornstone; that others secrete silica, which assumes the 
character of opal ; while others may possess the power of 
secreting and forming diamonds. 
It may be added, that the carbonate of lime, which oc- 
curs in all the rock formations, from the primitive granite 
to the newest alluvial formation, is one of the mineral sub- 
stances secreted by vegetables. Some lichens and the char^ 
tribe afford remarkable examples of this fact. 
