ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
103 
vature takes place in roots is transmitted in the cortex either of the con- 
vex or of the concave side, and that the root, in curving, takes advantage 
of tensions already existing. In an unstimulated root the tensions of 
the tissues are such that the tension on each side tends to curve the root 
away from that side ; when these tendencies balance each other, the root 
grows straight. The elasticity of the cell-walls forces water out of the 
cells into the intercellular spaces, and this shortens the cells on that 
side ; while, at the same time, the stimulus causes an extension of the 
cells on the side which becomes convex. 
(4) Chemical Changes (including Respiration and Fermentation). 
Formation of Chlorophyll.* * * § — From a series of experiments, made 
chiefly on Vida Faba and Phaseolus vulgaris , M. W. Palladine concludes 
that certain substances — saccharose, raffinose, glucose, fructose, maltose, 
glycerin, galactose, lactose, dextrin — promote the formation of chloro- 
phyll in the green parts of plants ; that others — inulin, tyrosin — appear 
to have no sensible effect ; while others, again — mannite, dulcite, aspa- 
ragin, urea, alcohol, ammonium chlorhydrate, quinic acid — retard or com- 
pletely inhibit the process. A larger amount of oxygen is necessary for 
the production of chlorophyll in vegetable tissues than for the process of 
respiration. 
Transformation of Saccharine Substances into Oil.f — From the fact 
CO 
that the proportion is less than unity during the earlier, greater 
than unity during the later period of the ripening of the olive, M. C. Gerber 
argues that oil has been formed at the expense of mannite or some other 
carbohydrate. 
A further series of observations leads M. Gerber to extend this con- 
clusion to fruits and oily seeds generally. The value of the proportion 
CO 
, dependent on this process, differs materially from that due to fer- 
mentation or to the production of acids. 
Formation of Proteids by Leaves. — According to observations 
made on a number of different plants by M. U. Suzuri,J the decrease at 
night of the amount of sugar and other carbohydrates in the leaves is 
associated with a decrease also in the amount of proteids. He concludes 
that leaves possess the function of facilitating the formation of proteids 
in all parts of the plant by assimilating nitrates, yielding thereby amido- 
compounds. 
M. E. Godlewski § states that proteids are formed from nitrates only 
in the light. The process is not, however, a direct one ; non-proteid 
compounds are first produced, even without the assistance of light ; these 
aro then converted into proteids only in the light. 
* Comptes Rendus, exxv. (1897) pp. 827-9; Rev. Gen. de Bot. (Bonnier), ix. 
(1897) pp. 385-91 (1 fig.). f Tom. cit., pp. 658-61, 732-5. 
% Bull. Coll. Agric. Imp. Tokyo, 1897, pp. 241-52. See Journ. Cliem. Soc., 1857, 
Abstr., p. 580. 
§ Ann.' Agron., 1897, pp. 310-24. See Journ. Chem. Soc., 1897, Abstr., p. 583. 
