30 



As shown hj the table, there was relatively a most striking decrease 

 of magnesia to lime in zones 1, 2, and 3 of the trunk of the seed 

 beech as compared with the corresponding zones from the control beech. 



The leaves of aquatic plants are also rich in lime. The pro- 

 portions of magnesia and lime were found to be, in JS^ymphcea lutea, 

 1 : 8.5 ; in Lemna^ 1 : 3.3 to 1 : 7.6 ; and in Elodea canadensis^ 1 : 8.4. Also 

 algae show similar i)roportions, as seen from the ash analyses of 

 Spirogyra nitida by Pennington (1896) and of fucoids by Godschens 

 (1854:). AlgcTB incrustated with calcium carbonate must, of course, be 

 here excluded. 



From what has been said under this head it will be seen that the 

 analytical investigations of the ash of plants show (1) that lime and 

 magnesia are present in every part of the plant, and [2) that the leaves 

 contain relatively more lime and the seeds relatively more magnesia 

 than the other parts of the plants. These characteristics can not be 

 accidental, but must be the result of certain functions. 



THE PHYSIOLOGICAL I3IP0RTANCE OF LIME SALTS IN PLANTS. 



The more leaf surface is developed in a given time, the more lime is 

 necessary. A normal crop of wheat requires per hectare (nearly .2.5 

 acres) about 11.6 kilos; sugar beets, 30.2 kilos; grass, 49.4 kilos; clover, 

 111.8 kilos; and tobacco, 153.7 kilos, while a normal growth of wood 

 needs annually about 20 kilos of lime, besides 7 to 16 kilos of mag- 

 nesia, 2 to 10 kilos of potash, and 0.8 to 4 kilos of phosphoric acid. 

 When the large demand for lime salts by plants is taken into considera- 

 tion, it is easily understood that an absence or deficiency of lime 

 becomes apparent very early. 



Stohmann^ kept maize shoots alive for some time in a culture 

 solution free from lime, but all development gradually ceased with the 

 consumption of the stored-ui) lime. However, when at the end of 

 several weeks some calcium nitrate was added, a very striking effect 

 was noticed, hardly five hours elapsing before new buds pushed out 

 from the sickly looking tips. 



Heiden ^ observed that maize and peas in culture solutions without 

 lime lived only four weeks, and reached respectively only 18.9 and 27 

 cm. in height. In culture solutions without magnesia, however, maize 

 lived ten to twelve weeks and peas lived eight weeks and attained a 

 height of 44 and 30 cm. respectively. In solutions without potassa or 

 phosphoric acid, but otherwise complete, such plants lived from eight 

 to twelve weeks. The absence of lime, therefore, was felt first, owing 



lAnn. Chem. Pharm., Vol. CXXI. 



-Centralbl. f. Agr. Chem., Vol. XVII, p. 622. Prianisbnikow observed that shoots 

 develop (luicker in a solution of gypsum than in distilled water, which fully accords 

 with the writer's observations. Seedlings of Phaseohts, Pisnm, and Ciicurhita kept 

 in distilled water die before all the reserve material is consumed. An addition of 

 a calcium salt to the distilled water leads, however, to the perfect exhaustion of the 

 reserve stores (Boehm, Liebenberg). 



