622 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
property of the root-tip. Under normal conditions the apical region 
itself, for a short distance, does not exhibit any considerable geotropic 
sensitiveness ; but this is the result of the tip being kept in passive 
equilibrium by the curvature of the more rapidly growing zone immedi- 
ately behind the apex. 
Expenditure of Labour in Geotropical Curvature.* — Herr P. 
Meischke has endeavoured to solve the problems connected with this 
subject in the cases of hypocotyls, epicotyls, and leaf-cushions. The 
results are given in a number of tables specifying the plant on which 
the experiments were made. 
C4) Chemical Changes (including Respiration and Fermentation). 
Synthesis of Albumen in Green Phanerogams.! — The chief results 
of a series of observations by Herr B. Hansteen on Lemna minor, Vicia 
Faba, and Bicinus communis, are as follows. Light plays no direct part, 
at least usually, in the synthesis of albumen in the green parts of flower- 
ing plants. Under favourable conditions of growth, albumen is formed 
in them without access of light, and at any time of the year. The pro- 
duction depends, however, on the presence at the time of special carbo- 
hydrates. The amides, amido-acids, and other nitrogenous compounds 
are not indifferently of use for the formation of albumen. The substance 
best adapted for this purpose is urea, which is rapidly transformed into 
albumen if accompanied in the cell by either cane-sugar or grape- 
sugar. 
Alcoholic Fermentation without Yeast-cells. t— Herren E. Buchner 
and R. Rapp draw the following conclusions from numerous experiments. 
(1) When yeast which has been well triturated with kieselguhr and 
quartz-sand, is fractionally filtered under a pressure of 60 kilos per 
square cm., the liquid which runs through first is far less active than 
the later fractions, the most active portion being obtained by a second 
trituration and filtration without the addition of more water. From 
1200 grm. of yeast with the gradual addition of 65 ccm. of water, 
730 ccm. of active extract may be obtained. When, however, the extract 
is filtered through biscuit porcelain, the* first 20 ccm. are much more 
active than any of the subsequent fractions. 
(2) Fermentation takes place equally readily with solutions contain- 
ing from 15 to 30 per cent, of sugar ; in such case toluene is added, 
and the temperature kept at 23°. When sugar is not present, very little 
fermentation takes place, the maximum amount of carbonic anhydride 
evolved from 20 ccm. of extract being, after 40 hours, 0’06 grm., and 
after 88 hours 0 * 1 grm. 
(3) Starch itself is not fermented by the extract, but “ soluble 
starch ” and dextrins of various origins are readily fermented. 
(4) Glucose and fructose are fermented at practically the same rate 
as one another, both by yeast extract and by fresh Munich bottom yeast. 
This conclusion is, however, not in accord with statements made by other 
authorities. 
* Pringsheim’s Jahrb. f. wiss. Bot., xxxiii. (1899) pp. 337-67. 
f Tom. cit., pp. 417-86 (2 figs.). 
X Ber. Deutscb. Chem. Gesell., xxxii. (1899) pp. 2086-94. See Journ. Chem. 
Soc., 1899, Abstr., ii. p. 606. Cf. this Journal, ante, p. 56. 
