d. During the msht this difference disappears where vegetables are
sown sparingly ; but where tliere is an accumulation of plants, and
they grow vigorously, even in the night the ozone observed in the



BOTANY. 315

plants is greater than in the air, which is, doubtless, explained by sup-
posing that the ozone disengaged during the day continues to surround
tiie plants during the night when the weather is calm. 4. Plants in
the country give off more ozone than those in the town during the
day, — probably due to vegetative life being more active, — the former
also reducing more carbonic acid. 5. Hence we may infer that the
air of the country and that of habitations surrounded by vast gardens,
forests, etc., is more vivifying than that of towns. 6. In the midst of
towns and a concentrated population, the ozone of the air at night b
more considerable than the ozone of the air by day. If we go away a
little from this concentration of men, and enter into that of plants, the
excess of the ozone of the night above that of the day diminishes ; and
if we advance further into the country, where plants are more numer-
ous than men, the ozone of the day oecomes more considerable than
that of the night 7. The interior of the corollas gives off no ozonized
oxygen. 8. In dwelling-rooms oxygen does not generally exist in the
ozonized state."

FHOSPHOBUS m VEGETATION.
