In a recent review Hassid (4) evaluated evidence concerning the re4'aittive roiles of GDP glucose and UDP gilucose in th-e synthesis of celldnlose in higher plfanit systems. Brumimonrd and Giblbons (1) found that celllobiose was a hydrolytic product derlived from the poly,saccharide whicoh resulted from utiilizatiion of eiither UDP gltcose or GDP glucose in a lupine enzyme syste,m. Ordin an'd Hall (5) found that GDP glucose in an oat colelopjtliile system reacted to fiorm a polysacehanacide Which, tupon hydrolysis by Streptomiiyces sp. QM B814 cellullase, produced essentiailly onily cellobiose. The polysaccharide produced from UDP gluicose, on thie other hand, yiedllded mostly celilohiose btnt a1lso some niixedl ,81,4-,81,3 triisacch'aride. W-e concluded that celltlose and a polylmer conitaining p1,3 and 81,4 linkages were produceid. Villeimez, Franz and Hassid (9) reporeted recently thiat mung bean partlicles cotuld allso form a product which could be hydrolvzed by acid to ce,1loibiose anld laminarihiose. We wi,sih to present furither evidence to substanli,alte that indeed at leas,t 3 84-ink polysacchianides, namely cedliluilose, cereail flour type glucan and laminarin, are produced from UDP glucose in one higher plant sysitem. We used a method different from thait reported earliier. Oat coleoptile section,s, 200 in number, were homogenized in 1 ml of 100 mm triis pH 8 plus 4 mm Nja2 EDTA in a glass tissue grinder. A 0.2 mll ailiquot of homogenate was removed for enzyme assay. The re-mainder was cenftrifuged at 1000 X g (max value) for 5 minutes. The supernatiain't soluttion wa,s receiltrifuged at 140,000 X g for 1 hour or 25,000 X g for 30 minutes. Tihe pellets were resuspended in 1 ml of tris-EDTA anid were recentnifuged. The pellets were finallly resuspended in 0.18 ml of specified sodluttion. A 0.05 ml aliiquot of homogenate oir h.igb speed pelilet was incubated in a to,tal voltume of 0.2 ml contaiiiing 4 ,umoles MgCl2, 0.4 iamole Nia, EDTA, 10 janoles tris and 0.7 mtjmole UDP glucose ('glucose-'C). Other :ad'dition's are noted in tables and figure. Inctibation was 15 or 30 minuttes at 250 as noted. Reaction was terminated by heating the dilutecl mixture in a boiling waater bath. One mg acid swollen celillutlose was added to the hIiigh speed pelleits but was omitted for homogenlafte tubes. Pelilets were extracted sequentiailly twilce witih hot wiater (temp of boiiling water bath) and tWice wvitih holt 1 N NaOH for 5 m!inutes each. After walshing out the alkali with water, the re?idues were swoV en by H3P04 trelatment except a,s indsicated and weire then subjected to hydirolyslis by 0.16 mig Streptomyces sp. QM B814 celilulase in 0.5 ml 2.5 mM phosphate at pH 5.8 at 500 for 24 hours. This cebludlase conitains primlarily p1,4 endo glucanase with traces of ,31,3 and P1,6 glucianases according to Reese and Man'dels (8). The solu;tiion was then developed 3 'times on S & S 589 White Ribbon paper in btitanol, pyridine, walter (30:10:15). The chromatographic ,strips were scanned in a Vangua-rd 880 Autoscanner. CeMlobiose activiity was axbit,rariily set to 1.0 for each chromatogram. As shown in table I, the 140,00 X g pellet prodtuced 3.5 times more ceillobiose than trisaccharide. The trisaccharide in the oat enzyme system wais shown by Oirdin anid Hallil (6) to be 4-O-laiminari'biosyl glucose (glucose 1-*3 glucose 1-4 glucose). Only a trace oif l,amiina;ribi,ose was found. Since the cedlilullaase is an endo glucanase, the cellobiose was probably randomily cleaved out ,olf the chain. The possibility of a siingle glucoise unit being added t-o the nonreducing en!d of an acceptoir and a dimer being cleaved endwise by the cedlulase was checked. Celilobiose from the syntheta,se product was treated wilth lead tetraacetate by the method of Charison and Perlin (2). Since both tiadioacdbive gluclose and radioadtive tetros!e were found, more than 1 gluco,se unit wals added per acceptor im'lcecule and it is probable that the aligosaccharides are infdeed derived from within the chain. The proportions of celRobiose and laminairiIhiosyl glucose inidica'te that the bulk of material 1 This investigation was supported in part by Research Gran.t AP-00213 from the National Center for Air Pollution ControT, United States Public Health Service. 2 Present addres.s: Scottish HorticulItural Research Institute, Invergowrie, Dundee, Angus, Scotland.