24 
REPORT— 1847 . 
continues to elongate until at last it attains to an enonnous length. Nothing 
like tins occurs under the influence of either light or hmt. It would appear 
that this abnormal condition is due to the excitement of the actinic rays, acting 
possibly with great power upon the living principle in the roots by which the 
elaboration of some organizable matter is produced^ which they supply as food 
to the stem; but, as there is but little power to decompose carbooic acid, there 
is not the necessary supply of carbon to give rise to tliosc stems and learfe 
which naturally form upon the primitive stem. 
That this is something like a true i^xplanation is further proved by the 
fact, that in the practice of phintirig shoots the use of blue mtflia is highly 
advantageous. It appears to inercaw! the tendency to the (levclopaieol of 
roots, and it is satisfactory to learn that some gardeners have, without any 
knowMgo of the cause, employed cobalt blue glasses to aid in Uie “ striking 
ol cuttings." Dr. Lindley (Theory <if Horticulture, j>. 215), referring to tie 
«»perinienis oi Dr. Daubeny, seems disposed to rcgaril the efii*cts described as 
due to the absence of light merely; it is however evident that the chemical 
principle of the solar beam materially assists in the development of new roots 
from cuttings. The formation of woody fibre depending on the sccrctiou of 
carbon from the carbonic acid absorbed by the leaves, and decomposed, by 
some functional power of the plant, under the influence of cxtenml excitement, 
,Jt has ever beeji considered important to determine if this was due to the lu¬ 
minous niys or to any others. 
The experiments of Semiebier (Mem. de Pliys. Cliim. tom. ii. p. 55) went 
to prove that jdants <lecomj)oscd the carbonic acid they aUorbed by the 
leaves much more readily under tlic influence of the violet rays than any 
I . j . * '* * cA|iHi Huc.ncS} (ind 
lielit^and ejirbotiic aidd increases with the increase of 
nlcr TlMa , r ‘r'" r "i"'" of the yellow ray than any 
dSmilJ „ «peri.nent, ,vl.-icl. I Imie already 
found i '%*!■'!"? “'“t IhtlarKer quantity of woody oiatter U 
nJ,n„tonigVia,tl». 
w nte™Mainfrl|'SoX’S 'Bn™th™” r P'?"”®’ leaves of planta in 
the tnoriifieil radiations after "y''-!''?*'''? *0 the ioHuemv of 
fpiantity of carbonic afilUio ^ of coloured media. Although the 
very dillerent, fur ihc sami> liberntwl by the plant is 
is evident that under anv cdrr.i! ’ conditions of radiation, H 
composition of the carbonic aciil is'effreT/ladmitted, the de¬ 
rapidity. cllected m some cases slowly, in some with 
rays is a fc»caou\lue‘m'’som^^ ‘‘***^ "‘Aacnee of the solar 
proveil the correctness of t for I have again and again 
theque Tiniversclle do Geneve) (®“Pl’*cment a la Bihlio- 
et broyGe ne ilonne plus do irno« i^ *'^\**° ‘‘sp^cedo fcuille qui a ^t6coupt’C 
de I’eau impregnte d’aeid earbonifiM?^"*"?^ flcand on I’cxpose au soleil dan* 
niore oxygon is given ofTfrom wr, *-• ^han this, Ihavo found that 
Iroui the plant; .and that viiii than fnmi a branch broken 
bm^.c^ than when .hey a 'Vom the leave, cut from the 
they exhibit groat.roVS^!;!'^^ acid in different rates, but 
eppareut from the following results Vi? influence. This will be 
b esujts. I be coloured media used were the same 
