Opt. 19, 1N33
den1 in detail 1vit.h thein here. The easy deliydrogenirtioii of chlorophyll hns led to thc suggestion tlint n reversible reaction clilorophyll + dcliytlrochlorophy I1 + 2H . siipplics the hydrogen for tJie photochciiiical rcdnct ion of carbon dioxide. Sclieines on this basis hnve been proposed 11. ConruitG5 and also Ly StolLGG WillstiittcrG' hiis given :in intcrprctntion in tcriiis of tlic riidicnl theory the to luiii nntl Ilnbcr. All tliesc suggestions are a t present piire speculirt.ion, t.liougli t.licy niny provide fruitfiil Iiypotliescs for experinicntnl work. There hiis bccn interesting work by EmcrsonG8 and by Eniemon iind id10 have used vcry siiccessfiilly the flirshg light nictliocl of WnrlJurg 011 t,lw green nlgn CkloreUo. Emerson's ciirly cslminiciits sceiiied to dliow ti ~iroportioniility Lctwecii the anioiint of pliotosyiit Iicsis iiud tlic chloropliyll coiltent of ;i ciilturc, t h s proving for the first tiiuc t hiit chloropl~yll int crveiies clicinicall\ in photosynthrsis, itlid not only iis IL pliotosensitizer.
Later cspcrinieiits, Iiowcvcr, show u much poorer corre- Iation.70 Pliotosynthtic cfliciency for IL given nniount of light eiicrgy is enormously iiicreasctl in iiitcriiiit tcwt light, and by : i n i q p i o i i s iiistliod the nites i i n t l t 110 order of the light iiud tliirk (I3liicklniin) rciiction iiiid other inforniatioii iirc oltiiinctl, for which reference inust Le made to tlic original p a p s . It. is not possible, Iiowever, to stiitc wltieli nioleculiir spceics is iuvolvctl in tlicsr rciict ions, iior whether, nor in \vliiit form, chloroliliyll iritcrwnes chcniic.:Jy. It has not yet. IiCell possible, tlicrdore, to iip~ily t lie atl-rtnc:es in the kuo~vledgc of the clieinicril structure of cltlorophyll to n solution of the photosynthesis problein.