NATUllAL CLASSIFICATION. 



121 



Tamarindus, Hymenaa^ Parkinsonian and even Cassia^ the 

 papilionaceous blossom assumes the appearance of pretty re- 

 gular four-leaved flowers. 



181. 



Another effect of abortion is, that an organ, which has com- 

 pletely altered its form, becomes incapable of performing its 

 function. It is then either altogether superfluous, and re- 

 mains only as an ornament (175,), or it performs the function 

 of another organ, whose form it has taken, — as the expand- 

 ed filaments of Canna and Thalictrum petaloideum supply 

 the place of the petals of the corolla. 



The usual eff*ect of abortion, in which another part is en- 

 larged at the expence of the abortive part, has been partly 

 noticed already. We thus see the fruit swell and be^'ome 

 better flavoured, when the seed is abortive. Thus, in the 

 Acacia of New Holland, the compound form of the leaves is 

 only remarked during the earliest growth of the plant. Af- 

 terwards the leaves become abortive, and in their stead the 

 leaf- stalk is evolved to such a degree, that, along with the 

 form, it assumes also the function of leaves. 



In fact, attention is every day more carefully directed to 

 the laws of abortion ; because by them we are able to explain 

 a great multitude of phenomena in the vegetable world, and 

 of otherwise incomprehensible varieties of form ; and because 

 excellent applications of these laws can be made to the phy- 

 siology of animal bodies. 



B, On Change and Degeneration of Parts. 



182. 



It is an important law of the whole vegetable kingdom, 

 that from every individual part of a plant, every other may be 

 evolved. In animal bodies of a perfect structure, this is not 

 possible in the natural state, because the internal structure of 

 the individual organs is much more compound and various. 

 It is only in the sickly state of the higher animals that muscle 



