ISFLUEXCE OF SOLAR RAYS 0 \ THE GROWTH OP PLANTS. I7 
Hesearches on the Influence of the Solar Rays on the Growth of Plants. 
Robert Hunt. 
with this investigation have been extended over 
fnH sea«'« of the year- 
and the locality )d which ^ey have been carried on hi been changed from 
metipolt ™ neighbourhood of the 
tieado'irid uhich renminopen for inves- 
of the r nh^ ^ '^’^amined, ro(,uire, from the complexity 
to ji h research, I believe 1 am enabled 
to lay before this meeting of Uie ihitish Association a serlw of important 
“f 8-.nina.iou and vegetal,le g^wtl,. on 
I “y '•‘■ports has been the *' Influence of 
abfvp’ ^ ^ changed that form of expression and adopted the 
agenev "f vegetation to tim 
mmr-mfL .‘f agencies which are not lumi* 
nous .latcnaJIy mduenco the phtenomena of vegetable vitality. 
isteuef or '"f® this place ou the probable ex- 
rare towl.il^r"''^’ ‘ll pnnciple distinct from light and heat in the sun's 
enfe’ the cunous chemical changes produced by solar influ- 
phierioniem the existence of throe distinct classes of 
ph^iomena, which cannot, I think, be disputed. 
TlirarTblirrM and chemical Mcilafion. 
portion loearclicj were ilircclod to solve, »m the pro- 
KXlJld by light, heat .and acliniata-as the 
SOW rmZTln ° p r'!'’';,"' tbo chemical phteaordfta of tl,c 
Tbp Tn^nn called—in the various stages of vegotahle growth. 
not very perfeM^- S ^1 “-Pirating tlicso phmndmeiia from each other arc 
sibJe t^hLfl -ri Hi the present state of our knowledge, it is impos- 
Xteiv™;’i?r/'' oPf'itioris of cither light, heat or actinism ab- 
have over t>ther. If we use the prismatic spectrum, wo 
under somp f amount of thenuie action, and, 
Sh havf of chemical power. In the violet rays, 
and heat • antt ^ * particularty distiuguished as chcmicai rays, we have light 
and actimV nf have decided proof of both luminous 
ic sDect?.,rL which have bemiinadewiU^ the pris- 
TliP aom not the comhmed effect of tlie thnw forces, 
inflitcrinfi ® J^utions apply to absorbent media, but the amount of each 
tBriliai.i vcMiIy determined ; and we are therefore enabled to refer any 
pamca lar rcult to a tolerably wcil-defiaed agccy. 
aciinn recorded in this rcjiort have been inailc under the 
which have permeated variously coloured media, 
that a i-£.u ^ coloured transparent fluids. It is not sufficient to state 
follnu-e^i employed, as it by no means 
cnlniii. .. media are perrooated only by the rays correspouding in 
TKftii re ^ 1 *^® influences duo to a given order of refrangibiUty. 
DiPflita i * to experiments made with coloured 
184-7 ^ strongly felt by other observers. Dr. Daubeny says in his 
