598 TRA NSLOCA TION 



were formed 1 . The endosperm of Ricinits grows to a certain extent 2 

 even when isolated, and this is accompanied by marked metamorphosis 

 of the reserve-materials. The latter may also occur in the absence of 

 any growth if the products do not at once exert an inhibitory restraining 

 influence, or if they undergo further changes, or are deposited again in some 

 other form. The potential powers which isolated organs exhibit may not 

 be called into play in the intact plant, or at least may not be exercised 

 to the full possible extent (Sect. 4). 



Hansteen was able to completely empty the non-growing and appa- 

 rently inactive endosperms of Hordcuin vnlgare and Zea Mays, by attaching 

 the surface normally in contact with the scutellum to a little column of 

 gypsum standing with its base in water (cf. Sect. 93). The same result is 

 obtained by direct contact with water if the remainder of the endosperm 

 is exposed to air and hence sufficiently supplied with oxygen 3 , while 

 since the entire absence of micro-organisms was assured in these experiments, 

 it is obvious that the mobilization and depletion are due to the activity 

 of the endosperm itself. The process ceases as soon as the products 

 accumulate to only a slight extent, and hence it soon stops if a small 

 quantity of water is used, while no conversion of starch is produced if the 

 endosperm is placed in direct contact with a solution of sugar. 



Different varieties of the same species possess this power in varying 

 degrees, and thus Puriewitsch found the endosperm of certain kinds of 

 maize might be completely emptied, whereas other varieties only underwent 

 partial depletion even when kept in contact with large quantities of water. 

 In such cases as these the aid of the secretory activity of the scutellum 

 is apparently necessary for complete depletion, and as a matter of fact 

 the scutellum is able to excrete large quantities of diastase and thus to 

 exercise a marked solvent action upon dead endosperm or upon starch 

 paste 4 . Diastase is apparently excreted into the endosperm by the 

 scutellum even when full depletion may take place without such assistance, 

 but it is always possible that the production and excretion of this accessory 



1 Van Tieghem, Ann. d. sci. nat, 1876, vi. scr., T. iv, p. 183. Cf. also Green, Annals of 

 Botany, 1890-91, Vol. iv, p. 383; Hansteen, Flora, 1894, Erg.-bd., p. 419; PfefTer, Ber. d. Sachs. 

 Ges. d. \Yiss., 1893, p. 422; also Puriewitsch, Ber. d. Bot. Ges., 1896, p. 207; Jahrb. f. wiss. 

 Bot, 1897, Bd. xxxi, p. i ; Griiss, ibid., 1895, p. 10 ; Landvv. Jahrb., 1896, Bd. xxv, p. 385 ; Linz, 

 Jahrb. f. wiss. Bot., 1896, Bd. xxix, p. 265. That the reserve-materials are deposited in living 

 tissues has been shown by Bredow, Jahrb. f. wiss. Bot., 1891, Bd. xxn, p. 349; Zimmermann, Beitr. 

 z. Bot. Centralbl., 1893, Bd. in, p. 430; Zacharias, Flora, 1895, Erg.-bd., p, 228. 



2 Mohl, Bot. Zeitung, 1861, p. 257. Cf. also van Tieghem, 1. c. ; Leclerc du Sablon, Rev. gen. 

 d. Bot., 1895, T. vir, pp. 162, 269; Zacharias, Flora, 1895, Erg.-bd., p. 234. 



3 Puriewitsch, 1. c., p. 209. Griiss (Ber. d. Bot. Ges., 1895, p. i) attempted to show that the 

 phenomenon was due to the action of the gypsum, but has since altered this opinion to one more in 

 accordance with the facts. 



4 Hansteen, 1. c. Cf. also the literature given by Hansteen (1. c., p. 426) and Griiss (Lar.dw. 

 Jahrb., 1896, Bd. xxv, p. 429) ; also Linz, 1. c. ; and Griiss, Jahrb. f. wiss. Bot., 1897, Bd. xxx, p. 645. 



