PHYTOGENY. 211 



air, and not sap, except in the period of adolescence, as 

 occurs in the animal kingdom. 



1068. The spiral vessels consist of one or several fila- 

 ments spirally contorted, and held together by a delicate 

 tubular-shaped membrane. 



1069. They must be regarded as elongated ceUs, 

 upon whose parietes the starch-granules have been placed 

 in serial juxtaposition with each other, so as to form 

 spirally-twisted filaments, as is to be plainly seen in many 



, cells and also in Confervse. This spiral condition origin- 

 ates without doubt from the spiral-shaped motion of the 

 granules in cell-sap. 



1070. The ultimate cause of this spiral motion, as well 

 as the position of the parts, appears to reside in the , 

 .rotation of the sun. 



1071. Upon T3iis also depends probably the winding 

 i of the stem of plants, with the spiral-shaped position of the 

 I leaves and branches, as probably even the contortions of 



the snail's shell and of the hairs upon the crown of the 

 j head. 



A 1072. The production of the spiral form originates 

 , from the antagonism of the light with the matter. The 

 number of spiral vessels is therefore less in those parts 

 that are beneath, than in those above, the earth, or 

 less in the root than the stem. The more indeed an 

 organ has been exposed to the air, by so much the 

 more do the spiral vessels preponderate, as e. g. in the 

 leaves. 



1073. An organ must necessarily be nobler in charac- 

 ter, the more spiral vessels it contains. The plant also 

 that, with more spiral vessels, exhibits them particularly 

 arranged, must take a higher rank. The lowest plants, 

 as the mushrooms, lichens and mosses, consist therefore 

 entirely of cellular tissue ; in the ferns therefore only a 

 single bundle of spiral vessels makes its appearance. 

 When plants become nobler, several fasciculi of spiral ves- 

 sels originate ; and in tracing this feature we ascend from 

 the ferns to the grasses and lilies, up to the lower Dico- 

 tyledons. In the higher Dicotyledons the packets of 



