ON THE INFLUENCE OF SOLAR RADIATION ON PLANTS. 377 
Tlic seeds experimented on were those of the wheat and the pea; and in 
every case both were employed, in order that if there should be a different 
effect of light on the monocotyledonous and dicotyledonous plants, it might 
be seen. Seeds of familiar plants and of great commercial importance were 
cIium a. as it was supposed a greater degree of interest would naturally attach 
to experiments on them, and it might happen that some observations of value 
to ilit* agriculturist might be made. 
The first series of experiments was made in common air, under the seven 
various influences of coloured light and obscurity which have been described 
in treating of the hyacinths. The coloured shades were arranged before the 
windows, as described above, aud they dipped into plates of water, so that 
throughout the experiments they were filled with un unchanged atmosphere, 
wturated with moisture. Twelve groins of wheat and twelve peas were 
taki n fur each separate experiment, and their weight was noted while they 
“•’re still dry. They were placed on bricks within the glass shades, the 
bncks standing in the water, so that they were always damp. Another 
arrangement was made, similar to that just described in every particular, ex- 
'ipt that the seeds were in the open air of the room, without any cover. 
the experiments were commenced on April 21st. The following is a 
. e 0 . the weather, and of the temperature taken in the shade at mid- 
tin^ * j l ^ e *' nie that the various experiments with peas and wheat con- 
M 
May 
April 22. 
,, 23. 
>. 24. 
.. 25. 
.. 26. 
» 27. 
.. 28. 
,> 29. 
30. 
1. 
2 . 
3. 
4. 
5. 
6 . 
7. 
8 . 
9. 
10 . 
11 . 
12 . 
13. 
14. 
hen c 
|*»'K 
cloudy 
May J5. 
fine 
09 
do. 
10. 
variable 
65 
do. 
„ 17. 
fine 
66 
variable 
„ 18- 
cloudy and wet 
61 
do. 
GO 
„ 19. 
fine 
66 
wet 
57 
„ 20. 
do. 
67 
variable 
50 
„ 21. 
... 
do. 
50 
„ 22. 
cloudy and wet 
64 
„ 23. 
fine 
65 
wet 
55 
.. 24. 
variable 
63 
variable 
„ 25. 
line 
66 
do. 
59 
„ 26. 
do. 
67 
fine 
01 
„ 27. 
wet 
63 
variable 
63 
„ 28. 
... 
cloudy 
00 
29. 
wet 
63 
56 
„ 30. 
do. 
63 
variable 
„ 31. 
fine, but cloudy 
65 
wet 
00 
fine 
66 
fine 
58 
„ 2. 
wet 
63 
cloudy 
02 
„ 3. 
fine 
65 
fine 
00 
„ 4. 
... 
cloudy 
64 
cloudy 
63 
05 
» 6. 
do. 
63 
h April ofi.u 11 Uie ,wo - 
the seven ni,* * U *; ;0|> n-seeds were found just beginning to burst 
end. p u JL Bses ’ 'hose under the obscured yellow' being the mot 
* under i|, 0 e { B l ‘°' v th whs visible the following day under thatglas 
under 
end. Po-ST”* ll,ose under the obscured yellow' being me most ad- 
1 under n,« e { ^ l0 " l h was visible the following day under that glass, and 
appear in an 8CUret * c °lourless, and the yellow, though the plume did 
‘"rlcsg mill || Ca * e ‘HI the 29th. On May 1st the radicles under the 
■ >Urp <l colouplo ° 8 , 08 " erG of considerable length, but those under the 
^ r,<l wpre longer, while the longest were under 
!up e4 colourll i n 29th plumes appeared under the red an 
88 {passes, and in the dark. They appeared two days later 
