434 EXPERIMENT STATION RECORD. 



aud partial desratlation of the products of inversion. When the fruits were 

 placed in nitrof;;en and air, it was found that after-ripening in the air pro- 

 ceeded uninterruptedly, while fruits kept in nitrogen remained unchanged and 

 preserved their starch content. This indicates that a free access of oxygen is 

 indispensable for the saccharification of the starch in the fruit. 



In studying the cause of the transformation in the case of the mango, it was 

 found that the juice contained a diastatic body with power to transform starch 

 into dextrin aud intt> sugar. 



Further investigations showed that the rapid transformation of starch into 

 sucrose during the after-ripening of some fruits is a vital process and not a 

 consequence of the presence of some ferment contained in the fruit. 



The hydrolytic and catalytic ferments acting during the process of ripen- 

 ing of fruit, G. Tallarico (Arch. FarmacoL 8i)er. e Sci. Aff., 7 (1908), Nos. 1, 

 pp. 27-.'i8; 2, pp. .'i9-68; aJ)s. in Chcm. ZenthL, 1908, I, No. 10, pp. 1^63, 1.56-i; 

 Jour. Chem. Hoc. [London^, 94 (1908), No. 550, II, p. 72.'/). — The author made a 

 study of bananas to determine the changes taking place during the px-ocess of 

 ripening of the fruit. " From this fruit, gathered in different stiiges of ripen- 

 ing, extracts were made. The catalytic action was determined by investigating 

 the action of the extract on hydrogen peroxid ; the amolytic, by its action on 

 starch ; the proteolytic, by the action on gelatin ; and the inverting, by the action 

 on sucrose. The following enzyms were present: Catalase, invertase, amylase, 

 tyrosinase, and a proteolytic enzym. The catalytic action is very intense so 

 long as the fruit is green and during ripening: it weakens as the fruit gets 

 black. The amylolytic action takes place when the fruit is green or at the be- 

 ginning of the stage of ripening; it then disappears. The inverting action is 

 almost entirely absent during the green stage, is intense during rir)ening, and 

 then gradualy disappears. The proteolytic action manifests itself during ripen- 

 ing, and then probably gets weaker." 



Transitory presence of hydrogen cyanid in ferns, M. Greshoff (Pharm. 

 Weekbl., J,5 (1908), No. 26, pp. 770-773; abs. in Jour. Chem. Soc. [London], 94 

 (1908), No. 550, II, p. 725). — The author reports the detection of hydrocyanic 

 acid in ferns, such as Gmiinogrammc aurea, G. lastrea, and G. athyrlum. The 

 percentage varied from 0.(».")6 in very young fronds to 0.006 in old ones, the con- 

 tent always diminishing with the increase in age of the material examined. 



On the effects of certain poisonous gases on plants, W. J. V. Osterhout 

 (Vniv. Cal. Pubs., Bot., 3 (1908), No. J,, pp. 339, 3.'fO).—The author has carried 

 on some experiments to determine a method of distinguishing the effect on 

 plants of smelter fumes aud other poisonous gases from that of drought and 

 similar natural causes. 



In some experiments on transpiration carried on some time ago, it was 

 noticed that in the case of drought the oldest leaves were the first to succumb, 

 while the youngest held out until the last. This was repeatedly confirmed with 

 cultures of the conmion wandering jew. 



When the problem of smelter fumes was called to his attention, it occurred to 

 the author that probably the effect of poisonous gases would be the reverse of 

 that of drought, in that the younger leaves would be affected before the older 

 ones. Experiments with wandering jew showed that the young leaves were the 

 first to be killed by sulphur dioxid, and these were afterwards confirmed by ex- 

 periments on fruit trees, grapevines, and other plants. Field observations have 

 since borne out the results of the experiments. 



It is believed possible, therefore, to distinguish between the effects of poison 

 ous fumes and natural agencies, such as drought and injury to the roots, in a 

 clear aud definite manner. 



