INFLUENCE OF SOLAR BAYS ON THE GROWTH OP PLANTS. 25 
as those described in the table, page 23. The relative proportions of mixed 
gas evolved is given, the proportions of nitrogen and oxygen not beine 
ascertained, as the object was merely to test the general sensibility to lumi- 
nous influence. Each set of the experiments, similarly numbered, were made 
at the same time, and all the conditions alike except the analysing media 
The comparison is made with the result of full exposure to bright sunshine’ 
the gas thus collected being considered as 100. ’ 
Yellow. 
Red. 
Blue. 
Mentha viridis. 
1 
64 
50 
47 
2 
70 
56 
51 
3 
68 
56 
52 
4- 
71 
55 
49 
Brassica oleracea. 
1 
79 
66 
37 
2 
81 
71 
4-4 
S 
73 
60 
42 
Mathiola incana. 
1 
63 
60 
58 
2 
62 
59 
55 
3 
67 
63 
60 
Salvia officinalis. 
1 
59 
51 
48 
2 
62 
58 
52 
3 
57 
51 
46 
4 
60 
56 
50 
It will be seen from these results that the common cabbngc-leavcs give 
more gas under the influence of the luminous rays than the others, but 
much less under tho influence of the actinic principle, combined as it is 
'VI 51 per cent, of light. On the contrary, the ten-week stocks and the 
giv'e lea gas than either the cabbage or the mint under liminous influ- 
^ much greater proportion under the influence of the che¬ 
mical and luminous rays combined. 
I have, Iroin numerous experiments which I have made, every reason to 
e iCTe that it will be found that there is as great a diflereiice between tho 
^ects produced on growing plants by the prismatic rays, as we know to Im 
roe on photographic preparaUons; the maximum effect altering, per¬ 
haps, lor every variety of jilaiit. 
induced to draw from these experiments are, that 
e luininous principle of the sun’s rays is essential to enable the plants to 
otteel the decomposition of the carbonic acid of the atmoBidiere and form 
e woody structure; tliat some plants require more light than others to 
j'* dcconiposition ; as, for instance, avc find the sage and ten-week 
stwks decomposing carbonic acid with less light than the cabbage or tbe 
mint; and it would appear that the increase of the luminous excitement be- 
yond a certmn point does not produce a corresponding increase in the quan- 
• / of gas liberated from the leaves of these plants. We may infer from all 
