1916] CURRENT LITERATURE 87 
absorb salts. The former bears salt in much higher concentration than in the 
latter, owing to excretion of carbon dioxide and probably owing to the presence 
of mineral acids freed because of the absorption of cations of salts** by the 
gels of the walls of the root hairs and epidermal cells.—Ww, CROCKER. 
Vegetation of an atoll.—Korpzum1% has visited and described the vegeta- 
tion-of an oceanic coral island lying in longitude 169°5 E. and latitude 6° N., 
contrasting the luxuriance of its vegetation with the poorness of its flora. The 
greater part of this atoll is covered with a luxuriant strand forest in which the 
cocoanut is prominent. ‘This is a response to a mean temperature of 27° C., 
and an annual rainfall of 450 cm. Of its 59 species, 40 seem to have reached 
the island by natural means. The largest families are the Gramineae (6 spp.), 
Euphorbiaceae (5 spp.), and the Leguminosae (4 spp.), their small representa- 
tion also pointing to the conclusion that the gal is altogether derivative and 
of comparatively recent origin——Gro. D. FULLE 
Parasitism of Comandra umbellata.—Investigating the conditions of 
growth of Comandra umbellata, because of its importance as one of the hosts 
of the heteroecious rust Peridermium pyriforme, so injurious to various pines, 
HeEpccock* found that in nature the plant is always a partial parasite, being 
united to its host by its roots and apparently most dependent in regard to its 
water supply. Fifty different hosts, scattered through various plant families 
from the Gramineae to the Compositae, are listed. Proof is cited that Coman- 
dra can live without parasitism, and that its seeds may germinate without the 
presence of the roots of host plants, although it is doubtful if it ever does either 
in nature—Gero. D. FULLER. 
Anatomy of Nephrolepis volubilis.—SAHN1’ has investigated the anatomy 
of this climbing Malayan fern. It is remarkable for its extremely long stolons, 
which scale forest trees up to 16 m., and enable the “lateral” plants borne 
on them at intervals to reach far above the mother plant, which is rooted in the 
soil. These lateral plants have no roots, and put out coiled tendril-like stolons 
that show contact irritability. The vascular cylinder of the stolons is an exarch 
protostele, and when a stolon branches, the two steles run parallel to each other 
for some distance, inclosed in the ni eer gehen tie eee ay become free. 
It is a case in which a soil-rooted plan n epiphytic 
progeny.—J. M. C. 
4 CzapEk, F., Jahrb. Wiss. Bot. 56:97-08. 19 
3s Kompzumi, Genicut, The vegetation of ee Island. Bot. Mag. Tokyo 
29:242-257. figs. 3. 1915. 
% Hepccock, G. G., Parasitism of Comandra umbellata. Jour. Agric. Research 
5: eae IQIs. 
37 SAHNI, BrrBaL, The anatomy of Nephroleps volubilis J. Sm., with remarks on 
the biology ae morphology of the genus. w Phytol. 14:251-274. pl. 4. figs. 7. 
TQI5. 
