were cut between 7 and 8 A.A. and taken directlv to the laboratory. The leaves w-ere promptly stripped off, and comparatively large samples of young anid of mature leaves were taken. Then 4-to 6-incll sections were removed from the base, middle, and tip of each shoot. The base and middle sections were divided into wood and bark. All samples were quickly cut into small pieces, weighed, and rapidlv dried in a small fruit dlehvdrater with a verv strong air blast at 600 to 630 C. The vines were cane pruned so that mature shoots (canes) could be sampled in the same mannier, except that there were
414PLANT PHYSIOLOGY no tip samples. Two 3-inch sections were sawed or cut from each trunk, the bark was removed, and the wood was separated according to annual rings: one-year-old wood and the subsequent growth during the sampling period, two-year-old wood, and wood three years old and older (two years' growth, including the pith). As soon as the trunk was removed, the root.s in the vicinity of the vine were dug up. After washing and drying of the external moisture, three types of root samples were taken: small rootlets (3/32-inch and less), one-year-old roots (3/16-to 1/4-inch), and two-year+ roots (1/2-to 3/4-inch). The one-and two-year root sections were divided into wood and bark samples. The dried samples were ground in a Wiley mill.Analytical procedure To obtain the sugars, the samples were continuously extracted with 95 per cent. ethyl alcohol for 6 hours by letting the condensed alcohol fall directly from the condenser onto the sample contained in alundum thimbles, the liquid level being kept above the material to help prevent channeling. The alcohol extract was evaporated to a small volume. The residue, taken up in warm water, was subsequently treated with an excess of neutral lead acetate, and the precipitated material was centrifuged off. The excess lead was removed with oxalate. Invertase was used for the sucrose inversion. The alcohol-extracted residue served as the sample for determining starch. The sample, plus 50 cc. water, was placed in an enclosed steam bath for one hour. Subsequently, 10 cc. of a phosphate buffer of pH 5 (4) and 10 cc. of the Taka diastase solution (2.5 per cent.) were added. Taka diastase utilized was purified, to remove most of the blank, by precipitation from a saturated water solution through the addition of 2.5 times its volume of 95 per cent. ethyl alcohol. The precipitate was centrifuged off and redissolved.The sample was then transferred to a porcelain jar, several flint pebbles were added, and the whole was rotated on its axis for 16 hours at 250 r.p.m.This procedure reduced the material to a very fine state of division, facilitating complete hydrolysis. If starch was revealed by a microscopical examination, the samples were re-treated. The extract was clarified, using lead acetate, and brought to a definite volume; and sufficient hydrochloric acid was added to make 2.5 per cent. by volume. The samples were then hydrolyzed in an enclosed st.eam bath for 2.5 hours. To determine th...
