650 



The results refer to young plants and show clearly how the production 

 falls off toward an upper and lower limit starting from an optimum tem- 

 perature for the roots. At the same time the figures also throw light upon 

 the difference in the warmth needed by the different species. Wheat (at 

 least when young) requires the highest soil temperature. Wheat developed 

 the most energetic assimilatory activity at 30 degrees soil temperature, while 

 rye developed best at 20 degrees and barley at 25 degrees C. 



Also in this young stage, when adjustment to conditions is easiest, the 

 plants clearly show the disturbing influence of too high a soil temperature. 

 Aside from the retardation of germination, a considerable difference was 

 shown in the habit of growth of the seedlings in that their stems and leaves 

 at high temperatures became thin and delicate while, at lower soil tempera- 

 tures, the specimens appeared short, thick and more fleshy. 



The experiments by v. Bialoblocki^ gave the same results and showed 

 also considerable diff'erences in the formation of the root system. The 

 barley plants, which were kept growing constantly at 10 degrees C, soil 

 temperature, had formed their roots from a few large, strikingly strong, 

 splendidly white branches of the jDrimary and secondary series, of which the 

 latter were unusually short and covered with small, wart-like protuberances 

 (latent eyes of the tertiary series). The individuals, standing in the soil at 

 30 degrees C, constant temperature, had developed unusual, richly ramified 

 brown root fibres, as thin as threads, which had become matted to a thick 

 felt. At 40 degrees C. the character of the root ball was the same but its 

 extent was very small ; a small felt was formed in the upper soil layers. 



Tolsky- also found in oats a stronger development of the individual 

 roots at a lower temperature and recently Kossowitsch-' confirmed these 

 results. The rate of penetration of the oats roots into the soil was retarded 

 thereby. A soil layer of about 30 cm., at the increased temperature, was 

 penetrated 14 days after seeding but, at the lower temperature, only after 

 30 days. 



Also in other experimental plants (mustard and flax) the weight of the 

 air dried roots was the greatest at a low temperature. The amount of 

 evaporation of plants grown under such conditions was less than for speci- 

 mens of similar development which had grown at the normal, or higher 

 temperature. 



Failure of the Pineapple. 



The fact, that pineapples grown in European conservatories surpass 

 imported fruit, because of increased flavor, has extended their cultivation 

 in private gardens in some regions (for example, Silicia). The greatest 

 danger in their cultivation lies in their "Durchtreiben," i. e., a continued 

 leaf growth at a time when the plant should enter its rest period in order 



1 Landwirtschaftliche Versuchsstationen 1871, Vol. XIII, p. 424. 



2 Journ. f. experim. Landwirtschatt, 1901, p. 730. 



3 Kossowitsch, P., Die Entwickelung der Wurzeln in Abhangigkeit von der 

 Bodentemperalur in der ersten Wachstumsperiode der Pflanzen. Journ. f. experim. 

 Landw. 1903; cit. Centralbl. f. Agrkulturchemie 1904, p. 451. 



