eS” 
1906] CURRENT LITERATURE 367 
Excretion of acids by roots—Kunzr”® has extended the work of Mo.iscu, 
PRIANISCHNIKOW, and CzAPEK on the general chemistry of the excretion of acids 
by roots, including a study of similar activity as exhibited by mycorhizal fungi. 
CzAPEK’s conclusion that the excretions do not contain free mineral acids is 
confirmed, but the presence of acid salts of the mineral acids is denied and the 
corrosive effect is attributed exclusively to the organic acids. Tests with about 
two hundred different species widely separated in systematic standing shows 
that many plants do not excrete enough acid from the roots to be detected by 
litmus. Fungi excrete much more actively and it seems probable that they are 
more potent as soil disintegrators than the roots of higher plants. The author’s 
work tends to increase his belief in mycorhizal symbiosis. Whether intentional 
or not it seems a serious deficiency to omit the date from 23 of the total number 
of 35 citations—RAyMoND H. Ponp 
Algae of northern seas—An interesting paper by Smmmons%° discusses the 
history and relation of the algal floras of the North Atlantic and North Pacific 
to one another and to that of the Polar Sea. The Atlantic and Pacific Oceans 
are believed to have received a large number of species from the Polar Sea of 
Tertiary times, especially just before the ice age, when the algae were driven 
southward. Some of these became established and never returned to their old 
situations, but settled and became variously modified in their new life ee 
Others re-entered the Polar Sea with the retreat of the ice. This is a paper w 
will bear careful study by those familiar with the algal floras of the North Meies 
and Pacific, especially in comparison with BORGESEN’s Algal vegetation of the 
Faeréese coasts noticed in this journal 41:71. 1906—B. M. Davis. 
Grape diseases.— BUTLER?" has published some observations on three grape 
diseases: red-leaf, shrivel, and root-rot. The red-leaf seems to be a disease closely 
related to diseases known as folletage, rougeot, and California disease. Like the 
other diseases named, the red-leaf is probably due to disturbances in the balance 
between absorption of water by the roots and transpiration. It is possible that 
the disease may be checked to a considerable extent by increasing the fertility 
of the soil so as to render the plants more resistant. The shrivel is found mostly 
among the white grapes and is also due to disturbed nutrition or deficiency of 
water supply. The root-rot is similar to if not identical with the disease described 
in French literature as pourridie. It is caused by one or perhaps several fungi 
not yet fully determined. It often kills the vines in a single season but it may 
only kill the vines after three or more years.—E. MEAD WILcox. 
9 Kunze, Gustav., Ueber Siaureausscheidung bei Pokecage und Pilzhyphen 
at tte ss Jahrb. Wiss. Bot. 42: 357-303- 
3° Smumons, H. G., Remarks about the relations at di floras of the Northern 
Atlantic, the Polar Sea, and the Northern Pacific. Beih. Bot. Centralbl. 19: 149- 
194. 1905. 
31 BUTLER, O., Observations on some vine diseases in Sonoma county, Cali- 
fornia. Bull. Calif. Exp. Stat. 168:1-29. 1 pl. figs. 1-5. 1905 
