864 The Exhalation of Ozone by Odorous Plants. [September, 
bedecked with or, somewhere in their loose cellular tissue, con- 
tain scented nectar which in many so-called inodorous flowers 
may not be sufficiently pronounced to be perceived by the organ 
of smell. 
It is a well-established fact that wherever fertilization is accom- 
plished by insects, so-called mectaries are somewhere found in the 
flowers. These organs are described by Sachs as follows: “ The 
nectaries are often nothing but glandular portions of tissue on 
the foliar or axial parts of the flower ; very often they project in 
the form of cushions of more delicate tissue or take the form of 
stalked or sessile protuberances; or whole foliar structures of the 
perianth, of the andrcecium or even of the gyncecium, are trans- 
formed into peculiar structures for the secretion and accumula- 
tion of the nectar.”? 
The proportion of plants where pollination is effected by insects 
is certainly large, and when we take into account those flowers in 
which cross-fertilization occasionally results from the aid of 
insects, this proportion is still very much larger. Whether it can 
be claimed for all inodorous flowers that they contain a greater or 
lesser number of nectaries we are not prepared to state, but it is 
certain that numerous flowers, which are classed as being without 
fragrance or any other odors, such as the geranium, the passion 
flower, etc., are visited by insects, and these must therefore con- 
tain glandular ‘tissues filled with an alluring secretion. The 
question also naturally here arises: Are there not flowers that 
are never visited by apects, which flowers possess these glandular 
organs? 
Our investigations did not include an examination of these 
organs, but there is evidently an interesting subject here pre- 
sented for further experimental study. 
The theory that the fragrant emanations from flowers, as well 
as all the various odoriferous substances emitted from plants, 
stand in close relation to the ozone-producing function in plants 
likewise receives striking corroboration in the well-known chemi- 
cal fact that the volatile perfumes and the strongly-scented aro- 
matic substances have the power to convert the oxygen of the 
atmosphere into ozone. 
e application of the results of our experiments to the rather 
"old but highly i ing subject of the cultivation of house plants 
isaw Text-book of Botany, p. 500, 
