SUMMARY OF CURRENT RESEARCHES RELATING TO 
quantity of proteinaceous matters. Light is essential to tlie growth of 
green plants because it brings about conditions favourable to the greatest 
activity of the proteinaceous substances which they contain ; it causes, 
by the promotion of transpiration, a flow of water from the root, and 
consequently a continuous supply of carbohydrates and mineral sub- 
stances. It has no influence on the changes in the nature of the pro- 
teinaceous substances. 
Formation of Resins and Essential Oils.* — Herr A. Tschirch states 
that resins or ethers are the principal constituents even of many solid 
hairs. Saponification produces aromatic acids, and a peculiar group of 
alcohols to which the author gives the name resin-alcohols or resinoles. 
The resins and essential oils are not simply excreta, but perform a 
biological function for the plant. The formation of resin does not take 
place in the epiderm of the secreting organ, but in the wall of special 
greatly swollen cells which faces the secreting canal, and in a particular 
mucilaginous portion of the wall. 
Formation of Starch in Pelargonium zonale. j — According to Dr. C. 
Acqua this plant belongs to the class in which the chloroplasts form 
starch-grains derived from substances already assimilated, or, in other 
words, in which the chloroplasts may be transformed into leucoplasts or 
starch formers. But, although at first the starch-grains are developed 
entirely from the leucoplasts, a layer of cytoplasm soon takes part in 
the process, and subsequently continues exclusively the formative pro- 
cess. Layers of protoplasm are thus transformed into layers of starch. 
The microsomes in the protoplasmic layer are probably the first to 
initiate the transformation ; they separate themselves from the hyaline 
protoplasm, and thus give rise to the formation of two distinct zones, 
which produce successively two layers of starch possessing different 
degrees of refrangibility. Hence the striated appearance of the layers 
of starch. 
Alkaline Reaction of Aquatic Plants.^ — Dr. 0. Loew has investi- 
gated the cause of the alkaline reaction of the water in which aquatic 
plants ( Elodea , Cliara) are growing vigorously. He determined that it 
is not due, as has been suggested, to the formation and excretion by the 
plant of an alkaline carbonate ; but either to the separation of an 
organic calcium salt, or to the passing of the calcium carbonate excreted 
by the leaves into a colloidal condition, in which it is dissolved by 
organic substances. 
7. General. 
Vegetable Heat.§ — M. G. Bonnier states, as the result of a series of 
observations on the heat evolved by generating seeds and by opening 
flowers, that the rise of temperature is by no means necessarily the 
result of the production of carbon dioxide ; it may be produced by the 
oxidation of other substances than carbon, or by doubling, or by hydration. 
This last is a very important source of heat, which has commonly been 
neglected. There are two maximum periods of the evolution of heat, 
* .Tahrb. f. wiss. Bot. (Pringsheim), xxv. (1893) pp. 370-9. 
t Malpighia, vii. (1893) pp. 393-6. % Flora, lxxvii. (1893) pp. 419-22. 
§ Ann. Sci. Nat. (Bot.), xviii. (1893) pp. 1-35 (2 pis.). 
