300 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
observations on this subject. Leaves assimilate in light three times as 
much saccharose as in the dark. In the presence of saccharose the syn- 
thesis of proteid substances takes place more energetically in the light 
than in the dark. The regeneration of proteid substances goes on 
more energetically in the blue half of the spectrum than in the yellow 
half. The presence of a large reserve of carbohydrates and the action 
of light are indispensable for the normal formation of living nitrogenous 
substances in the leaves. 
Assimilation of Carbohydrates.* — According to M. Maze, the higher 
plants can live, like those which are destitute of chlorophyll, at the 
expense of organic substances already formed, when protected from the 
light ; but, in the natural condition, this power is feeble compared to 
that possessed by Fungi and Schizomycetes. 
Delation between the Depth of Colour of Leaves and Chlorophyll 
Assimilation. f — As the results of a series of experiments on a number 
of different plants, M. E. Griffon finds that the depth of the colour of 
green plants cannot be relied on as a measure of the intensity of chloro- 
phyll assimilation. Although in most cases leaves of a deep green 
display a greater energy that those of a lighter tint, yet in other cases 
leaves of the same tint possess very different powers of assimilation, or 
those of a lighter tint may even be more energetic. The thickness of 
the mesophyll and of the palisade-tissue, and other points of structure, 
are factors in determining the depth of coloration of the leaves. 
Assimilation of Nitrates by Plants.^ — From a series of experiments 
on the absorption, distribution, and assimilation of nitrates, chiefly by 
cultivated crops, Herr T. Wolfer draws the following general conclu- 
sions. Plants grown in the dark store up nitrates more rapidly and more 
abundantly than those grown in the light. Plants grown either in the 
dark or in the light, or in an atmosphere containing a larger amount of 
carbon dioxide than the normal, contain no starch, and only traces of 
glucose. Nitrates could be detected only in small quantities in the 
vascular bundles ; a larger quantity in the bundle-sheaths ; the largest 
quantity in the cells of the cortex and parenchyme. 
Growth of Viburnum lantanoides.§ — According to Miss Ida A. 
Keller, this shrub begins its growth normally with a main axis, ending 
in a terminal and two lateral buds. A tendency soon becomes evident 
towards retarding the growth of the main axis, while the chief energy 
is transferred to the lateral branches. There is a further tendency to 
the complete suppression of one of the lateral buds. The true axis is 
hence often replaced by a false axis, and the species has a decided ten- 
dency towards the sympodial method of branching. 
Transpiration. || — Mr. H. H. Dixon regards transpiration as a vital 
rather than as a physical phenomenon, i.e. as a process which can take 
place only during the life of the organism. The elevation of the water 
of the transpiration current, when the leaves are surrounded by a satu- 
* Comptes Rendus, cxxviii. (1899) pp. 185-7. f Tom. cit., pp. 253-6. 
f Beitr. z. Kenntniss d. Aufgabe u.s.w. d. Nitrate in landwirthsch. Cultur- 
pflanzen, Rostock, 1898, 61 pp. and 7 pis. See Bot. CentralbL, Beih., viii. (1899) 
p. 278. § Proc. Acad. Nat. Sci. Philadelphia, 1898, pp. 482^4 (1 pi.). 
|| Proc. R. Irish Acad., iii. (1898) pp. 618-35 (3 figs.). 
