( 447 ) 
envelopes, to the way in which the floral leaves are arranged in 
the bud, with reference to each other, (the aestivation) to mutual 
coalescence, io the presence of scales, hairs and glands, to the 
secretion of water, honey, mucilage, etc. Also, if we give promi- 
nence to the protection of the generative organs as the basis of our 
considerations, we shall have to investigate whether the secretion of 
nectar is not connected with this protective function. 
This connexion may be inferred all the more readily on account 
of the unmistakable correspondence of the secretion of nectar during 
the flowering period to that of water or of a mucilaginous fluid in 
the so-called water-calyces, the latter secretion being considered a 
means of protection of the sexual organs. 
With regard to this secretion of water I beg to recall, that 20 
years ago Treus first drew attention to the remarkable phenomenon 
that the floral buds of Spathodea campanulata Bravv., a tropical 
Bignoniacea, are filled with a watery liquid, secreted by a large 
number of glands, which cover the inner surface of the calyx, so 
that the petals, stamens and ovaries develop under the protection of 
this fluid. The liquid contains traces of the hydrochlorides, carbonates, 
nitrates and sulphates of potassium, sodium and calcium, has an alkaline 
reaction and contains traces of ammonia; sugar was not found in it. 
A similar secretion of water in the closed flower-bud was after- 
wards also observed in other plants. We may mention the papers of 
LAGERHEIM, GREGOR Kraus, HALLIER, KOORDERS, SHIBATA and SvEDELIUS, 
to whose investigations [ do not propose to refer here in further 
detail, as I intend to publish my own observations on this subject 
before long. From these it will be evident, that the phenomenon is 
not limited to the tropics, but can also be studied here. 
I only wish to emphasize, however, that all naturalists, who have 
occupied themselves with the subject, have accepted the opinion of 
TrevuB, that the secretion of water is a means of protecting the sexual 
organs against the unfavourable consequences of too strong transpira- 
tion, and that my personal observations, especially in this country, 
have shown me the connexion between the secretion of water and of 
nectar, and have gradually confirmed me in the conviction, that 
by the nectar-secretion the sexual organs are protected. 
I wish briefly to explain the train of thought, from which I started 
my investigation. 
The observations on plants with water-calyx and especially the 
detailed investigations of Koorpers have taught us, that already long 
before the corolla and the sexual organs are laid down, the very 
30* 
