28 EXPEMMENT STATION EECORD. 



jiud they haA-e been unable to find jirbutin in any except the species producing 

 the fruit Ivuown as the pear. On this account they thinli the test could be used 

 in differentiating the species into separate genera. The proportion of arbutin 

 was found to vary in pear leaves according to the stage of gi'owth ; however, 

 it was still to be found at the end of the growing season. 



A study was made of the relation of arbutin to autumn coloring of pear 

 leaves, and some varieties were found to blacken, as claimed by Weevers 

 (E. S. R., 24, p. 138), due to the oxidation of the arbutin. In some varieties, 

 however, the leaves turn yellow instead of black, and this is attributed to the 

 presence of methylarbutin in conjunction with the common glucosid. The 

 methylarbutin hydrolyzes more rapidly than arbutin and results in a yellow 

 coloration. 



The behavior of tannin in persimmons, with, some notes on ripening, 

 F. E. Lloyd (Fhnit World, U, (1911), .A'o. 1, pp. 1-1.',, pi. 1).—A study has 

 been made of the tannin in ijersimmons with special reference to changes 

 taking effect on ripening. 



Ttie author found that the tannin in the tannin cells of the unripe fruit 

 does not exist wholly in a watery solution, but is rather associated in part 

 with a carrier somewhat analogous to a gelatin, albumin, or other colloid- 

 tannin compound. The insolubility of the tannin in the ripe fruit is due to 

 its intimate and complete association with the carrier, with which it unites. 

 The behavior of the tannin is considered analogous to that of other substances 

 which are rendered insoluble by combination. 



The final stages of ripening of this and similar fruits are believed to be inde- 

 liendeut of living protoplasm, and this conclusion is confirmed by experiments 

 in which chemical agents have been used to induce ripening earlier or more 

 rapidly than normal. 



In the normal tissue there is no intercellular tannin. When such occurs it 

 is probably due to the bursting of the tannin cells through bruising or other 

 injury. The capacity for imbibition on the pai*t of the tannin masses sufli- 

 cient to burst the cell wall is not associated with astringency to the taste 

 during the whole of the period of riiiening when such bursting is possible. 



In the course of the investigations the author obtained evidence showing 

 that the cell walls of the pulp are digested and that they are not composed of 

 true cellulose, but pectocellulose. 



It is probable that the above conclusions are applicable to the ripening of 

 the date. 



The effect of the frosts of the winter of 1908—9 on vegetation, F. J. 

 Chittenden (Jour. Roy. Hort. Soc. [London], 36 (1910), No. 2, pp. SoS-.'tO-',) .— 

 The author gives detailed accounts of the effect of abnormal temperatures 

 occurring in England on the growth of a large number of introduced plants. 



Plant acclimatization in southern Arizona, J. J. Thornbeb (Plant WoPld, 

 14 (1911), No. 1, pp. 15-23). — The author gives an account of observations on 

 attempts to acclimatize plants in southern Arizona, in which perennial plants 

 from temperate zones were subjected to high summer temperatures and those 

 from subtropical and tropical regions to possible frost. These two factors seem 

 to be the limiting ones in determining the possibility of introducing a consider- 

 able number of economic and other plants. Notes are also given on the influence 

 of soil, soil water, elevation, etc., on the introduction of plants. 



The weeds of arable lancf in relation to the soils on which they grow. 

 Miss W. E. Brenchley (Ann. Bnl. [London], 25 (1911), No. 91, pp. 155-165).— 

 An attempt has been made to ascertain how far weeds of arable lands are char- 

 acteristically connected with particular soils and crops. 



