6 Messrs. Brown and Escombe. On the Depletion of the 



of contact with the plaster, a fact which the author attributes to the 

 accumulation within the endosperm of an excess of soluble products, 

 which thus exercise an unfavourable influence on the continuous 

 chemical change of the solid reserve substances. 



In view of Haberlandt's assertion that the cells of the " Kleber- 

 schioht " have a distinct diastase-secreting function, Hansteen 

 experimented in a similar manner with endosperms which had been 

 deprived of this layer, and he found the same indications of self- 

 depletion as before. He therefore concluded that the dissolution 

 and depletion which he had observed are due to a special activity of 

 the inner starch-bearing cells of the endosperm. The question is 

 then discussed whether, during germination, the embryo does or 

 does not secrete an enzyme, and the conclusions arrived at are in 

 accord with those of Brown and Morris, and Griiss, that such a secre- 

 tion does take place. Hansteen, again agreeing with the former 

 observers, regards this secretion of diastase as conditioned by the 

 falling off in the supply of readily soluble carbohydrates; whether, 

 however, the diastase so produced plays an important part in normal 

 depletion, or whether the asserted self-depletive power of the endo- 

 sperm-cells is sufficient, in normal germination, to account for all the 

 observed results, the author leaves an open question. 



In a long memoir entitled " Beitrage zur Physiologic der Kei- 

 mung,"* J. Griiss discusses the question of the appearance of fer- 

 ments in the endosperms of maize and barley after excising the 

 embryos and filing off the " Kleberschicht " (" aleurone-layer "). 

 From experiments made by burying fragments of such endosperms 

 for a few days in sterilised moist sand, he concludes that the starch- 

 bearing cells have the power of producing spontaneously within 

 themselves a diastase, the presence of which he determined, in the 

 first place microscopically by the extremely doubtful guaiacum-reac- 

 tion, and secondly by the increased action of the endosperm-tissue 

 on thin starch-paste. 



The most recent contribution to the subject is a paper, taking the 

 form of a preliminary communication, by K. Puriewitsch, "Ueber 

 die selbstthatige Entleerung der Reservestoffbehalter,"t followed since 

 by a more detailed paper, entitled " Physiologische TJntersuchurigen 

 iiber die Entleerung der Reservestoffbehalter."^ Making use in the 

 main of Hansteen's method of experiment, Puriewitsch examined, 

 amongst other seeds, the isolated endosperms of Zea Mays, Triticum 

 sativum, Hordeum distichon, Secale cereale, and Oriza sativa, and he 

 extended his observations to the cotyledons, bulbs, rhizomes, and 

 roots of various other plants, a list of which is given in his paper. 



* ' Landwirtschaft. Jahrbiicher,' 1896, p. 385. 

 f ' Ber.-Deut. Bot. Gesell.,' vol. 14, 1896, p. 207. 

 J ' Pringsheim's Jabrb.,' vol. 31, 1897, p. 1. 



