ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
215 
tion. The stigmas are developed only after the hairs on the style, which 
have collected the pollen, have withered and fallen. 
Flowering of Arum pictum.* — Prof. Gr. Arcangeli has noted the 
elevation of temperature which takes place within the spathes during 
the flowering of this species ; the maximum elevation observed being 
8*1° C., at 9.80 a.m. The insects which find their way into the spathe 
and assist in the transport of the pollen to the female flowers are very 
numerous, by far the greater number being Diptera. In one case, out 
of 149 insects captured, 120 belonged to one species of Diptera, Lirno- 
sina simplicimana ; in another case, out of 200, 191 were Diptera, the 
remainder being Coleoptera and Hymenoptera. The author altogether 
disbelieves the alleged carnivorous habit of this or of other species of 
Arum, such a phenomenon being, in fact, inconsistent with the part 
played by the insects in pollination. 
(2) Nutrition and Growth (including- Germination, and Movements 
of Fluids). 
Conduction of Organic Food-Materials in Plants.! — Observations 
made by Dr. F. Czapek on leaf-stalks lead to the following conclusions. 
The carbohydrates find their way from the leaf to the stem through 
the leptome-bundles, and not through the parenchyme of the petiole. 
The conducting tissues of the leptome-bundles are exclusively the 
sieve-tubes and the cambiform cells ; the leptome-parenchyme and the 
medullary rays serve no other function than that of storing-up of food- 
materials. In addition to starch, sucroses are a widely distributed con- 
tent of the sieve-tubes. Protoplasm-threads and the streaming of pro- 
toplasm are not essential factors in the transport of formative materials 
through the leptome ; the most active factor in the process is the absorp- 
tion and excretion of the transported substances through living proto- 
plasm. The independent life of detached portions of a plant, and their 
development into new individuals, are, in general, the results of a sen- 
sitive reaction, caused by the cessation of the interchange of formative 
substance with the mother-plant. 
Effects of Tropical Insolation.^ — Dr. A. J. Ewart gives the result 
of a large number of observations on exposure to the direct rays of 
the sun in the case of plants grown at Buitenzorg. He finds that, if 
prolonged, the insolation may markedly affect, or temporarily inhibit, 
the functional activity of the assimilating parts. If the stoppage is 
temporary, it is generally accompanied by but little change in colour; 
but if permanent, the chlorophyll-grains may become completely 
bleached. The leaves are protected against the injurious effects of ex- 
cessive exposure by the presence of a red pigment and by active or 
passive paraheliotropic movements. The active movements are best 
shown in the motile leaves of the Leguminosa3, the pulvini being the 
motile and irritable perceptive organs. The red pigment acts mainly 
and primarily as a protective shield against the more refrangible green 
and blue solar rays. It has also a feeble heat- absorbing power, which 
* Bull. Soc. Bot. Ilal., 1897, pp. 293-300. 
t SB. K. Akad. Wiss. Wien, cvi. (1897) pp. 117-70. 
X Ann. of Bot.,xi. (1897) pp. 439-80 and 585. Cf. this Journal, 1897, p. 311. 
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