200 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
shortly after the stem has been sharply struck. This irritability i& 
transmitted by the vascular bundles in an ascending line until it reaches 
the flowers. Here it acts first of all on the calyx, the lamina of the 
sepal rising, with a more or less rapid movement, till it leans against 
the corolla and compresses it, pushing it continually forward, until it 
falls off from its own weight. This detachment is facilitated by the 
existence of a separating zone of very small cells intermediate between 
the large ovoid or oblong cells of which the lamina of the corolla is 
composed and the large rounded cells of the receptacle. A similar 
structure occurs in the leaves. 
(4) Chemical Chang-es (including- Respiration and Fermentation). 
Diastatic Ferments, in Plants. — From a series of experiments on a 
number of species ( Canna , maize, Platanus, date, Phaseolus, Begonia , &c.) 
Dr. J. Griiss * comes to the conclusion that there exists in seedlings a 
soluble diastase which is capable of diffusion through the cell-wall in 
the same way as sugar. It appears to pass, with maltose, out of the 
cotyledons into the stem. The removal of the cotyledons diminishes 
the amount of diastase in the stem. The quantity of diastase present 
was ascertained by its action on starch ; the iodine-test being used to 
determine the extent to which the latter had been destroyed. In woody 
plants the chief seats of formation of diastase are the cambium and the 
pith. 
The same author | has observed the action of natural diastase on the 
endosperm of the date, and applies the term alldolysis to the mode in 
which it takes place, the penetration of the diastase into the substance 
acted upon being accompanied by a simultaneous change in the latter. 
The action on the reserve-cellulose is very slow, and ends in its trans- 
formation into soluble products, probably mannose. It is by this action 
of diastase that the absorption of the reserve-cellulose is effected in the 
germinating date. 
Influence of Oxygen on Alcoholic Fermentation.^ — Dr. E. Giltay 
and Herr J. H. Aberson have carried on a series of experiments for the 
purpose of testing the correctness of Pasteur’s view that yeast assumes 
its fermenting properties only when there is no free access of oxygen. 
The general result at which they arrived is that, in the presence of a 
gas containing a larger proportion of oxygen than that in atmospheric 
air, the amount of sugar which yeasts split up into alcohol and carbon 
dioxide is greatly increased, 
y. General. J 
Bastin’s Laboratory Exercises in Botany. § — This bulky volume is 
the first attempt, as far as we are aware, to combine a macroscopic and a 
microscopic text-book of botany. It is divided into two parts, — “Organo- 
graphy” and “ Vegetable Histology ” ; both relating to Flowering Plants 
only, the whole range of Cryptogamy being left almost untouched. The 
first part comprises the subjects of an ordinary handbook of Morpho- 
* Jahrb. f. wiss. Bot. (Pringsheim), xxvi. (1894) pp. 379-437 (2 pis.) Ber. 
Deutsch. Bot. Gesell., xiii. (189.7) pp. 2-13 (1 ph). 
f Ber. Deutsch. Bot. Gesell., xii. (1894) Gen.-Vers.-Heft, pp. 60-71 (2 pis.).’ 
X Jahrb. f. wiss. Bot. (Pringsheim), xxvi. (1894) pp. 544-86. 
§ Philadelphia, 1895, 8vo, 540 pp., 87 pis. and 7 figs. 
