ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
73 
influence of the different rays of light on transpiration was less easily 
determined. The absolute amount of transpiration was greatest in yellow 
light, least in the blue ; but this seems to be due to the necessary con- 
nection between the intensity of transpiration and the development of the 
transpiring organ. The results were obtained by growing the plants 
behind glasses of different colours. 
From a series of experiments made on the growth of various plants 
behind glasses of different colours, M. A. M. Villon * states that the vine 
produces a greater weight of grapes, which also contain a larger quantity 
of alcohol and of acid, when grown behind glass coloured red-violet by 
manganese, which absorbs the yellow and brown rays. Flowers are also 
favourably influenced by the same colour, which is, moreover, advan- 
tageous to the growth of yeast, bacteria, and silkworms. 
Influence of Light on the Structure of the leafy Cactacese.f — Prof. 
H. Vochting has carried out a series of observations on the leaf-producing 
Cactacese (chiefly Phyllocactas and Lepismium ), from which he draws the 
conclusion that the phyllotaxis is largely dependent on light. By altera- 
tions in the intensity and direction of the light he was able to produce 
changes in the arrangement of the leaves, and even in the structure of the 
stem. The “ wings ” of Phyllocactus appear to be induced by the direct 
action of the light on them, and not indirectly by its action on the grow- 
ing point. In Bhipsalis pctradoxa , on the other hand, the angles of the 
stem are developed even in the dark. The conclusions of the author 
differ from those of Schumann, J who refers the arrangement of the foliar 
organs on the stem to the space available for their formation in the 
growing point. 
Influence of Light on the Buds of the Copper-beech.§ — From a 
series of observations made on the copper-beech, Herr L. Jost finds 
that in this tree, contrary to what takes place in other cases, the putting 
out of the. bud is dependent upon light. 
Influence of Light on Diastase. ||— According to Prof. J. R. Green, 
light, whether solar or electric, exercises a destructive influence on dia- 
stase. This influence is, however, confined to the violet end of the 
spectrum, the remaining rays being slightly favourable rather than 
destructive. In the grain of barley the colouring matter of the husk acts 
as a screen to protect the diastase from the destructive effect of light. 
(3) Irritability. 
Heliotropism.^J — Dr.W. Rothert records the results of a large number 
of observations on the heliotropic curvatures of seedlings, of which the 
following are the more important. 
If a portion of an organ is illuminated on one side only, the helio- 
tropic irritation may be transmitted to other portions of the organ which 
are either illuminated on both sides or on neither. This transmission 
* Bev. Scient., i. (1894) pp. 460-3. See Bot. Centralbl., lx. (1894) p. 144. 
f Jahrb. f. wiss. Bot. (Pringsheim), xxvi. (1894) pp. 438-94 (5 pis.). 
t Cf. this Journal, 1891, p. 366. 
§ Ber. Deutsch. Bot. Gesell., xii. (1894) pp. 188-97. 
HI Ann. Bot., viii. (1894) pp. 370-3. 
1 Beitr. z - Biol. d. Pflanzen (Cohn), vii. (1894) pp. 1-212 (60 figs.). Cf. this 
Journal, 1893, p. 70. 
