ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
299 
Bacillus subtilis, on an Oscillatoria, and on the leaves of the sensitive 
plant. 
Physiology of the Flower.* — From observations made on a very 
large number of flowers, M. G. Curtel draws the following general con- 
clusions. 
The respiratory power of the flower is, in general, higher than that 
of the leaves; even when the calyx is green it exceeds the power of 
assimilation ; while in the bud assimilation preponderates over respira- 
tion. The respiratory power of coloured flowers is higher than that of 
white in the same species. Transpiration is more energetic from petals 
than from foliage-leaves, even to the extent of three or four times as 
much. 
All the parts of the flower — peduncle, calyx, and corolla — acquire a 
more vigorous development when growing in the sun than in the shade, 
and the tissues are more completely differentiated. In the shade the 
flowers are slower in appearing, smaller, less numerous, and less brightly 
coloured ; the fruits are fewer, and contain fewer seeds. 
Adaptation of Leaves to the Intensity of Light.f — Prof. J. Wiesner 
proposes the term photometric for those leaves which assume in light, 
and in consequence of illumination, a definite position in order either to 
obtain as much light as possible, or to screen themselves from too intense 
light ; while leaves which do not possess this property are aphotometric. 
Photometric leaves are either euphotometric or panphotometric ; the former 
are those which adapt themselves to obtain the maximum of diffused 
light ; the latter those which adapt themselves to both direct and dif- 
fused sunlight. The former are characterised by assuming a fixed 
position at right angles to the direction of the strongest diffused light. 
The vegetation of forests and plants which grow in deep shade present 
the commonest and clearest examples of euphotometric leaves. The 
“ light-absorption ” ( Lichtgenuss ) of a plant is the relationship of the 
intensity of the whole of the daylight to the intensity of the light at 
the spot where the plant grows. Expressing this by L, then the value 
of L varies between 1 and 1/100. Euphotometric leaves have always a 
dorsiventral structure. The leaves of all pines are aphotometric ; those 
of grasses take, as a rule, no fixed light-position. 
Effects of the Sun and of Shade on Vegetation.^ — Comparing the 
dried weight and the chemical composition of the ash of plants grown 
in the shade and fully exposed to the sun, especially in the case of 
grasses (Cynosurus cristatus ), M. Berth elot states that the richness of 
carbon in a plant is greatest when developed in the sun, least in the 
after-math. Phosphorus and sulphur, on the other hand, are present 
in the largest quantity in plants growing in the shade. The proportion 
of nitrogen is nearly the same in both. Plants growing in the shade 
appear more vigorous, but this is owing to the suppression or retarda- 
tion of the function of reproduction. 
Influence of Light on the Formation of Nitrogenous Substances.§ 
— M. W. Palladin gives the following as a summary of his recent 
* Ann. Sci. Nat. (Bot.), vi. (1898) pp. 221-308 (5 pis.). 
t Biol. Centralbl., xix. (1899) pp. 1-15. Cf. this Journal, 1896, p. 540. 
X Comptes Rendus, cxxviii. (1899) pp. 139-45. 
§ Tom. cit., pp. 377-9. Rev. Gen. de Bot. (Bonnier), xi. (1899) pp. 81-105. Cf 
‘this Journal, 1896, p. 542. 
