
_ EXPERIMENTS WITH SALINE SOLUTIONS 239 
injurious influence of direct sunlight on Bacteria is 
avoided. 
Can Silicon replace Carbon, ether wholly or partially, 
wn Protoplasm ? 
What I have to say on this important subject may 
be prefaced by some quotations from my book ‘ The 
Beginnings of Life,” ! in which a brief reference was 
made to this question. 
‘Another subject now claims our consideration. 
Living matter being the result of a chemical com- 
bination of a certain kind, there is no absolute 
improbability in the supposition that the carbon 
usually existing in the living compound might be 
replaced by some other element. With the hope of 
throwing some little light upon this very difficult 
subject, I made several tentative experiments with 
saline solutions containing—in addition to nitrogen, 
oxygen, and hydrogen—some other element in the 
place of carbon. The element with which the 
carbon was replaced was either silicon, boron, 
chromium, aluminium, or iron.? Except in those in 
which carbon was replaced by silicon, no living 
things have been met with in any of these solutions 
(after they had been boiled and the necks of the 
flasks had been sealed during ebullition). This 
result—taking it merely for what it is worth—is 
1 Vol. i., ADpenaizx A, p- 1x, 1872. 
2 As I have already stated, these experiments were merely tentative. 
It is not supposed that solutions were employed free from all trace 
of carbon, existing as an impurity. 
