1885. ] The Exhalation of Ozone by Odorous Plants. 863 
with the making of such tests, and on the other, the brilliant and 
very uniform success of the experiments made with pine foliage; 
it will be readily conceded that these facts furnish abundant evi- 
dence of the power the odorous principles evolved from the pine 
tree have to generate ozone 
From the foregoing, in conjunction with former investigations 
into the same subject, we are, at present writing, justified in formu- 
lating the following conclusions; 
First. That flowering plants, including odorous and inodorous, 
generate ozone, the former, however, much more actively than 
the latter. 
Secondly. That so far as tested scented foliage does possess 
the power to produce ozone, and. in the case of pine or hemlock 
foliage in a marked degree, 
Thirdly. That inasmuch as no reactions \gdedttéd on rainy 
days, it is highly probable that the function demands the influ- 
ence of the sun’s rays or at least good diffused light. 
In comparing the present with former conclusions, cited at the 
commencement of the paper, it will be seen that they differ in so 
far as relates to foliage plants only, those pertaining to flowering 
vegetation being perfectly concordant. 
As to the mode in which the ozone is developed by plant life, 
or in other words, as to what is the nature of this ozone-gener- 
ating function, the following explanation was elsewhere merely 
suggested (loc cit.) : “It is known that the ashes of seeds con- 
tains large quantities of the phosphates. It follows that during 
the formation of the seed there is a rapid metastasis of the phos- 
phorus in the form of phosphoric acid, and the phosphates to 
that organ of the plant, and it may reasonably be supposed that 
in the chemico-vital interchanges going on in the ovules, phos- 
phorus is liberated and acted on by the moisture which the 
leaves are so actively transpiring. * * * The subject, how- 
ever, merits further investigation.” In view of the facts estab- 
lished by present researches the theory of the production of 
ozone by vegetable growth above cited must be abandoned, and 
it appears evident, from present premises, that in some way the 
odoriferous principles emitted, whether from flower or foliage, are 
chiefly concerned in its formation. It is true we are unable in 
this manner to account for its production by odorless flowers, 
unless, as many contend, we grant that all blossoms are either 
