PHANEROGAMIA : AXIAL ORGANS. 233 



must be noticed that relation between two succeeding internodes 

 where they do not lie in a straight line, but form with one another 

 an angle which is often definite (caulis geniculatus}. Very often 

 the main axis, from being made up of undeveloped internodes 

 alone, which gradually die from below upward, remains always 

 under ground as an underground stem or trunk (caulis, truncus 

 hypog&us). 



It is wholly false to ascribe universally to nascent plants, a direction 

 absolutely vertical to the earth. As the germination of Viscum on the 

 side or under surface of a branch proves, the direction of the plant in 

 general stands in no relation at all to the direction of gravity of the 

 earth. The axis of every plant originally grows in a straight line away 

 from the level of the soil in which it is fixed, and properly never alters 

 this direction ; but the internodes already formed often take another 

 position, from the causes mentioned in the paragraph above. More 

 remains to be said about this hereafter, under the head of Germination. 



The causes of the spiral twisting of the axis round itself, or round a 

 foreign object, as well as of the knee-like bending of the nodes, are alto- 

 gether unknown. "We have from Mohl* an excellent treatise on the 

 point ; but he was not able to discover the cause. I will here very 

 briefly discuss the terms right and left wound stem, in regard to which 

 much confusion prevails. The natural conception is this : The plant is 

 developed from below upward, consequently it ascends ; if, now, we use 

 the expressions left and right concerning the plant, this can only have a 

 meaning when we place ourselves in its position ; but we turn to the 

 left in ascending if we have the axis of revolution to the left, to the 

 right if we have it to the right. If we refer it to the course of the sun, 

 we can evidently, in regard to our northern hemisphere, only bring the 

 southern half of each revolution turned toward the sun into relation 

 with its course, and then the right wound spiral would go with the sun, 

 the left wound against it. Linnaeus f strangely used these terms in the 

 opposite way, evidently starting from an obscure conception ; and many 

 others have followed him therein. Many have quite reversed the thing, 

 called left right, and right left, till the whole matter had become con- 

 fused. The reference to the course of the sun is moreover a very im- 

 perfect mark. It appears to me, however, that left and right wound 

 cannot well be understood in any other way than that which I have 

 given. 



In conclusion I will add, that all the peculiarities here mentioned are 

 equally shared by the axes originating from buds. In reference to the 

 first point, it must be recollected that the bud is a plant, the base of 

 which is limited from the very origin ; that consequently the primary 

 and natural direction of its growth is in a line perpendicular to the plane 

 passing through its base. Sometimes, but not often, this direction be- 

 comes changed in the subsequent internodes into one parallel with the 

 main axis. 



c. Of the secondary Axis. 



128. Buds may originate in the axil of every leaf (axillary 

 buds), or, under favourable circumstances, at any point on a woody 



* Von den Rzinken uncl <loin Winden der Sclilingpflanzcn. 

 f Philosopliia Botanica, ed. 2. Gluditsch, p. 39. 



