218 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
without spots ; and suggests that it may be connected with the attrac- 
tion of insects for the purpose of pollination. 
£. Physiology. 
(1) Reproduction and Embryology. 
Fertilisation of the Bromeliacese.* — Herr E. Ule has examined the 
structure of the flower in connection with fertilisation in several species 
of Brazilian Bromeliaceae belonging to the genera Nidularium, Quesnelia , 
. JEchmea , and Chevallieria. They frequently exhibit the phenomenon of 
cleistopetaly or pseudo-cleistogamy , i.e. the corolla is nearly or quite 
closed, and the flowers are nevertheless habitually cross-pollinated, 
usually by humming-birds, which open the corolla by their beaks, being 
attracted either by the scent, or by the bright colour of the corolla or 
of the bracts. Self-pollination is, however, not impossible ; and cleisto- 
petaly may often be a step towards cleistogamy. With the Bromeliaceae 
these flowers pass gradually into ordinary open flowers. 
(2) Nutrition and Growth (including Germination, and 
Movements of Fluids). 
Organic Nourishment of Green Plants, j — Dr. T. Bokorny discusses 
the reason why chlorophyllaceous plants are able to assimilate certain 
organic compounds, while others are useless to them. Thus C0 2 is readily 
^converted into CeH^O^; while plants cannot form any carbohydrate 
out of C s H 8 0 3 (glycerin). As a general rule, compounds with one atom 
of C are readily assimilable, the difficulty increasing with the increase 
in the atoms of C ; those which contain C and H only are not so favour- 
able as those which consist of C and 0 only, or of C, H, and 0. Pepton 
is a peculiarly excellent food-material for Fungi, and probably also for 
Algae. Starch can often be formed from grape-sugar or cane-sugar only 
through the influence of light. Free acids are always injurious to the 
protoplasm. Asparagin is readily converted into proteids in the dark. 
CH 2 0 (formic aldehyd) is probably always the first product of assimi- 
lation. 
Influence of Light on the Growth of Plants.^ — A series of experi- 
ments on this subject by Herr K. Stameroff leads him to the following- 
conclusions : — The vegetative hypliae of Mucor and Saprolegnia grow 
with equal rapidity in light and in dark. Light has a retarding effect 
on the growth of the reproductive hyphae of Mucor. The rhizoids of the 
bulbils of Mar chantia] poly morpha grow more slowly in the light than in 
the dark. Light has no effect on the rapidity of growth of the pollen- 
tubes of Colutea arborescens or 1 lobinia pseud-acacia. The vegetative 
hyphae of Mucor and Saprolegnia and the rhizoids of the bulbils of Mar- 
cliantia grow entirely at the apex. The pollen-tubes of Colutea and 
Bobinia exhibit irregularities in their growth, the variations following 
the law of the great period. The rate of development of the pollen- 
tubes, and their size, depend on the supply of sugar. 
c * Ber. Deutsch. Bot. Gesell., xiv. (189G) pp. 407-22 (1 pi.). 
t Biol. Centralbl., xvii. (1897) pp. 1-20, 33-48. 
% Flora, lxxxiii. (1897) pp. 135-50. Cf. this Journal, 1896, p. 540. 
