ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
179 
species of Orchis , and the non-chlorophyllous saprophytic species like 
Neottia nidus-avis and Corallorhiza innata. Although Limodorum con- 
tains abundance of chlorophyll, the chloroleucites are masked by a great 
quantity of a violet pigment in the stem, leaves, and all parts of the 
plant ; in consequence it has but little power of decomposing carbon di- 
oxide directly, and the respiration is always considerably in excess of 
the assimilation. 
Elongation of Hodes.* * * § — M. P. van Tieghem points out that the in- 
crease in length of an axial organ is not always due to the lengthening 
of the internodes only ; the nodes may take a share in this elongation, 
or it may even take place exclusively in them. This occurs, e.g., in the 
cotyledonary node of Cyperacese and Graminese, and in the short branches 
of various Coniferas. In the genus Buxus the author describes three 
distinct modes of elongation of the axis. 
Biology of Helleborus fcetidus.f — Prof. F. Ludwig points out the 
various contrivances by which this plant adapts itself to its enviromental 
conditions, especially the following: — The plant has two distinct forms 
of leaves, winter and summer, or “ chionophilous ” and “ chionophobous ” 
leaves. The summer leaves have broad strongly serrate lobes ; while 
the winter leaves are thicker and have narrower entire segments. 
When the temperature falls below the freezing point, they deflect their 
petioles so as completely to protect the plant against cold and snow. 
This protection enables the inflorescence to develop very early in the 
spring, when the flowers are pollinated by Hymenoptera. The ripe 
seeds bear a remarkable resemblance to Coleoptera-larvse, and are car- 
ried away by ants, which play an important part in their dissemination. 
Sap-pressnre.J — According to Dr. W. Figdor, the phenomena of sap- 
pressure ( BluttmgsdrucJc ) differ widely in temperate and in tropical 
climates. In the tropics (Java) there is always, in contrast to the pre- 
valent conditions in our latitudes, a positive sap-pressure which varies 
greatly in intensity in different plants. It is not unfrequently three 
times as great as in our climate. In one instance a pressure of more 
than eight atmospheres was measured. Even in the same plant the 
sap-pressure may vary greatly in the course of 21 hours ; these variations 
being due not exclusively to a periodicity, but also to external factors, 
such as transpiration. 
Transpiration in the Tropics and in Central Europe. — Herr E. 
Giltay § replies to the criticisms of Haberlandt on his previous state- 
ments, and especially lays stress on the view that the method adopted 
by Haberlandt of registering the amount of transpiration from cut leaves 
and branches is not a reliable one. 
To these objections Haberlandt |] makes a final reply. 
Elective Absorption of Mineral Elements by Plants.^ — By growing 
very young plants in very dilute mineral solutions, M. E. Demoussy has 
* Ann. Sci. Nat. (Bot.), v. 1897 (1898) pp. 155-60. 
f Oesterr. Bot. Zeitsehr., xlviii. (1898) pp. 281-4, 332-9 (3 figs.). 
X SB. k. Akad. Wiss. Wien, May 20, 1898. See CEsterr. Bot. Zeitsehr., xlviii. 
(1898) p. 359. 
§ Jalirb. f. wiss. Bot., xxxii. (1898) pp. 478-502. Cf. this Journal, 1898, p. 417. 
|| Op. cit., xxxiii. (1898) pp. 166-70. 
4 Coraptes Rendus, cxxvii. (1898) pp. 970-3. 
