129 



Glassy Grain Kernels. 



These must also be considered as the result of climate influences. 



Grains are called glassy when their endosperm is hard, almost trans- 

 lucent and grey or reddish in cross-section, while in the normal mealy 

 kernel the endosperm appears soft, white, porose and easily friable. 



This glassiness of the kernels occurs usually more abundantly in the 

 north and east of Europe than in the west, which fact points to the influence 

 of atmospheric dryness with a higher light intensity. In damper, western 

 regions the vegetative organs obtain a greater ascendancy. Thus Lieben- 

 berg^ states, for example, that the otherwise excellent northern barley has 

 two disadvantages ; — viz., too large a percentage of glassy grains and too 

 dark a color which is caused by rain falling on the grain when ready for 

 harvesting. These gusts of rain at harvest time naturally play no part in 

 the development of grains which mature during the dry season. With the 

 lengthened light action, varieties of rye also become intensively colored. 

 The same author reports that at the grain exhibition in Sweden, the oat 

 samples, on an average, possessed only 22.66 to 32.04 per cent, of chaff by 

 weight, while in the Austrian and French varieties it fluctuated between 

 25.23 and 38.37 per cent. In general there is truth in Haberlandt's" state- 

 ment, that a continental climate produces glassy grains, but that, on the 

 other hand, cool, wet summers or an artificial abundance of nutritive sub- 

 stances and water produce mealy, specifically lighter grain kernels, poorer 

 in nitrogen. 



The glassy condition of the grain, according to Gronlund's^ investiga- 

 tions on mealy and glassy barley, exists in the fact that the cells of the albu- 

 men in the mealy grain which contain the starch show that the spaces 

 between the starch cells are filled with cell-sap, while in the glassy grains 

 these spaces are filled with protoplasm. Johannsen's* work assumes a 

 greater air content not only between the walls of the mealy grains, but in 

 their whole mass. In germination, the glassy grains become mealy. Ac- 

 cording to Gronlund, who, moreover, acknowledges no relation between 

 weather and the production of the glassy conditions, glassy kernels germi- 

 nate more easily and better and give stronger plants. Although he assumes as 

 mcontestible that glassy kernels may be produced from soil containing much 

 nitrogen, yet he believes that poorer, sandier soil, poorly cultivated, pro- 

 duces this peculiar formation much more certainly. He found that mealy 

 grain was produced by pure potassium fertilisation. Moreover, both forms 

 occur at times in different stages in the same head. I would like to assume 

 for the production of glassy kernels that the process of starch formation is 



1 V. Liebenberg-, Bericht uber die allgemeine nordische Samenausstellung etc., 

 1882, cit. Bot. Centralbl.. 1882. No. 43, p. 115. 



^ Haberlandt, Die Abhangigkeit der Ernten von der Grofse und Verteilung der 

 Niederschlage. Oesterr. landw. WochenbL, 1875, p. 352. 



3 Nach einer Preisscheift des A^erf. cit. im Jahresbericht f. Agriculturchemie 

 XXIII (1880), p. 214. 



* Allg-. Brauer- und Hopfenzeitung-, 1884, Nos. 78 and 79. 



