218 BIOLOGY. 



2, EARTH-ORGAN. STALK. 



1096. The stalk is the idea of the whole plant, posited 

 under the import of the organ of nutrition, of the vessels. 

 The structure of the stalk is therefore accordant with that 

 of the root. The anatomical systems are alike in both, 

 bark, liber and tracheae being in the same envelope. 



1097. In the stalk, however, the opposition of tissues 

 and systems emerges more strongly, and therefore they 

 all become individualized also to a higher degree. The 

 spiral vessels become more freed from the cellular tissue ; 

 the bark is more distinctly divided from the liber ; this 

 again from the wood, and in its centre the cellular tissue 

 dries up into pith. As, however, the stalk is the first 

 product of the light-influence, the tracheal system cannot 

 attain as yet entire freedom. The cells have nevertheless 

 been extended, and the intercellular passages are formed 

 into regular tubes. The Stalk is the trunk of the plant 

 with a preponderating system of tubes. 



1098. This separation of the tissues and systems, with 

 the endeavour upon the part of each to become indi- 

 vidually perfect and isolated from the other, is effected 

 by the air and the light. As root imbibes the mucous 

 or slimy water, and sustains the chemical process 

 in the plant, so does the stalk set the water in motion, 

 since it exposes it to the air and light, whereby the 

 chemical earth-process becomes separated into different 

 saps and elemental bodies. 



1099. Through the influence of the air, light and heat 

 upon the stalk, as well as by its antagonism with the 

 root, its elongation is determined. The greater amount 

 of energy of the aerial polarity is in the higher regions ; 

 it is thus more excited by these than by the lower, and 

 the bud being lighter grows more rapidly in the upper 

 parts, and obtains an elongated form. The excitation is 

 stronger also upon the side exposed to the light. It 

 grows also more strongly in that direction, and thus the 

 stalk stands indeed upwards, but somewhat inclined from 

 the perpendicular line towards the sun. 



