ON THE INFLUENCE OF SOLAR RADIATION ON PLANTS. 379 
On Juue5tb, the experiments were stopped. The plants under the colour¬ 
less glass were healthy in every respect, and were of a better green than any 
of the others, Under the red glass, one of the plants was found to have 
shot up several small leaflets outside the transparent sheath, which it had 
been unahle to pierce. 
The following table shows the number of seeds of wheat which had put 
forth roots, and the average length of the principal roots; and also the 
number of seeds from which plants had grown, together with the average 
length of the principal leaves. 
Roots. 
Leaves. 
No. of plants. 
Length. 
No. of plants. 
Length. 
Colourless . 
10 
2’5 inches 
10 
10 inches 
Blue .. 
6 
075 „ 
6 
4 ,, 
lied . 
8 
3'5 „ 
4 
•1 „ 
Yellow . 
7 
2 !! 
(1 
9 „ ' 
Obscured colourless. 
6 
3d „ 
3 
2 o 
Obscured yellow 
i 5 
;:i a - } 
7 
8 „ 
Dark . 
1 2 
7 
2 5 „ J 
3 M 
6 
13 „ 
a ue plants were removed from the bricks, spvead out on the table, and 
allowed to dry in the air for eighteen hours. The following table shows the 
I ( /f those which had grown under each of the various conditions of 
'ght. The original weight of the twelve corn-seeds was in each instance 
grains, giving as the average weight of each seed 0‘66 gr. 
i Colourless 
| Blue . 
Red . . 
I Yellow .. 
I SS* CUred colourless' 
°hjwn«,l yellow ... 
|J'r‘ n r? s * in we 'g ,lt of the plants which had grown under the colour- 
"ukr f aud tbe yellow glasses, was due, of course, to the fixation of 
of Ml h„° r 11610 was 00 supply of carbonic acid from the air, and the quantity 
ivry triHhj C g W lich the roots could absorb from the bricks ,nUSt lmVe bee “ 
air or°»u mparative ex P p >'iuient in which the seeds were exposed to the open 
• v, n : n hl , r °?. m lii(l not come to anything. Not one of the seeds succeeded 
ditir ever p 1 le tun,c > doubtless because the dry atmosphere preveu e 
The mw * s nfficieut moisture, . , 
air, wol ?! sod a ^out the germinating seeds, or a constant change o 
•n t|,i 8 si.ri PP0b r by bave modified these results; yet the conditions observed 
ftll! effect J?,i f, x P c 'rt merits were thought necessary, in order to have the 
^easarit. , ^di'erent sorts of light about the seeds themselves, for a soil 
Purees J P '° 1 duccs Partial, if not total obscurity. The deprivation of other 
c ‘rtain Du J! ,bon * be ytiud the cotyledons of the seed itself, also answered 
h«i drawn 0,1 exa, uining the results, the following conclusions may 
’ ar as wheat is concerned growing under the conditions o 
No. of plants 
which had 
germinated. 
Weight. 
Average weight 
of each. 
Average in¬ 
crease upon 
original weight. 
10 
31 grs. 
3-1 grs. 
2'4 grs. 
0 
4 „ 
O' G6 „ 
8 
4-5 „ 
0 56 „ 
-o-i „ 
7 
8 „ 
11 ». 
0*4 „ 
G 
4 ,, 
0-60 „ 
0 „ 
7 
10 „ 
1-4 „ 
0'7 ii 
7 
9 ” 
1*3 i, 
0 - 6 ,i 
