376 M. C. Lea on the Influence of Ozone, ete. 
(2.) Carbonic Acid. 
Experiments were made to ascertain the effect of a complete 
removal of carbonic acid from the atmosphere surroundin 
plants. The seeds were placed on gauze strained over a ae 
of water, which was set in a dish containing concentrated solu- 
tion of caustic soda, and the whole was covered with a bell-glass, 
A similar arrangement was made, exclusive of the caustic alkali, 
to afford a term of comparison. 
No appreciable difference could be observed. It is probable 
that seedlings, within the height which they can attain under an 
ordinary bell-glass, still derive a sufficient supply of carbon from 
the seed. Be this as it may, the removal of carbonic acid from 
the atmosphere surrounding them did not interfere with their 
growth. 
Experiments made with seeds placed in an atmosphere of cat- 
bonic acid accorded with results obtained by other observers, a8 
to total prevention of germination under circumstances other 
wise favorable. The seeds, however, were found to be not in 
any way injured, and germinated freely on exposure to the at 
mosphere. ee 
It seems probable that in those cases in which germination 
has been observed to take place in an atmosphere of carboni¢ 
acid gas,’ the exclusion of atmospheric air has not been'sull- 
ciently well maintained. 
(3.) Simple and Compound Ethers. 
Seeds were placed on gauze under a bell-glass, as before, and 
an open narrow-mouthed vial containing a little ether was Intro 
duced. Germination was entirely prevented. 
Nitrate of methyl produced a similar effect. 
(4.) Organic Acids in Solution. 
Two organic acids were selected for experiment: oxalic adi 
as being reducing, non-nitrogenous and sharp; picric act 
issolved in water 
lutions 
d 
small 
resulted from the acid reaction of the solutions, other so 
of acid as before, viz.: three-tenths of one per cent. | 
neutral solution of oxalate, a slow germination followed; 12 
* Lindley, Int. to Botany, p. 359. 
