164 MORPHOLOGICAL DEVELOPMENT 



and subservient organs of fructification display, are thus 

 accounted for : we have seen reason to think them otherwise 

 caused. But I mean that the morphological characters which 

 distinguish gamogenetic axes in general from agamogenetic 

 axes, such as non-development of the internodes, and dwarf- 

 ing of the foliar organs, are primarily results of failure in 

 tho supply of some material required for further growth.* 



241. Another trait which has to be noticed under this 

 head, is the spiral, or rather the helical, arrangement of 

 parts. The successive nodes of a phgenogam habitually bear 

 their appendages in ways implying more or less twist in the 

 substance of the axis ; and in climbing plants the twist is such 

 as to produce a corkscrew shape. This structure is ascribable 

 to differences of interstitial nutrition. Taking a shoot that 

 is growing vertically, it is clear that if the molecules are 

 added with perfect equality on all sides, there will be no 

 tendency towards any kind of lateral deviation ; and the 

 successively-produced parts will be perpendicularly over one 



* It is but just to the memory of "Wolff, here to point out that he was im- 

 mensely in advance of Goethe in his rationale of these metamorphoses. Whatever 

 greater elaboration Goethe gave to the theory considered as an induction, seems 

 to me more than counter-balanced by the irrationality of his deductive interpret- 

 ation ; which unites mediaeval physiology with Platonic philosophy. A domin- 

 ant idea with him is that leaves exist for the purpose of carrying off crude juices 

 that "as long as there are crude juices to be carried off, the plant must be pro- 

 vided with organs competent to effect the task ;" that while " the less pure fluids 

 are got rid of, purer ones are introduced ;" and that " if nourishment is withheld, 

 that operation of nature (flowering) is facilitated and hastened ; the organs of the 

 nodes (leaves) become more refined in texture, the action of the purified juices 

 becomes stronger, and the transformation of parts having now become possible, 

 takes place without delay." This being the proximate explanation, the ultimate 

 explanation is, that Nature wishes to form flowers that when a plant flowers it 

 "attains the end prescribed to it by nature ;" and that so " nature at length at- 

 tains her object." Instead of vitiating his induction by a teleology that is as 

 unwarranted in its assigned object as in its assigned means, Wolff ascribes the 

 phenomena to a cause which, whether sufficient or not, is strictly scientific in 

 its character. Variation of nutrition is unquestionably a " true cause " of vari- 

 ation in plant-structure. We have here no imaginary action of a fictitious agency ; 

 but an ascertained action of a known agency. 



