to be led, hy the mere similarity of fbni), to suppose Uial, 

 therefore, the organs are ahke, has fallen into a mistake 

 which may give occasion to important errors. 



Experience teaches us, that when, from some peciiiiaritv ol" 

 structure, a function cannot be performed by tlie oi-o-an com- 

 monly destined for that purj)ose, another organ supplies its 

 place. As the proboscis of the Elephant performs the ])art of 

 a hand ; as the tail of the Kangaroo, although fashioned like 

 other tails, serves the animals as a bone ; so in the Acacia of 

 New Holland, the leaf-stalks supply the place of leaves 

 Thus, also, those leaves of water plants, which grow under 

 the water, are divided in the manner of rf)()ts, and seem to 

 perform a siniilar function 



175. 



There is yet another law to be understood, t(^ ena!)le us to 

 judge properly respecting the Nature of Organs. In innumer- 

 able instances, there appear forms similar tt) those which are 

 connected with a definite function, but which do not fulfil 

 that function ; and Nature seems, in these instances, as in 

 the animal kingdom, to produce forms which are completely 

 useless, merely for the sake of a harmonious and symmetrical 

 stnicture. The appearance of filaments with empty anthers 

 in flowers that are altogether female, and of female parts in 

 flowers wholly male ; the structure of filaments in other 

 forms, where tliey resemble nectaries ; the false nectarothi cas 

 in such Orciiidea^ as have no nectaries ; these all are forma- 

 tions which can only be explained by tlie law of nature we 

 are now illustrating. 



The third mean of knowing the Nature of an Organ, con- 

 sists in the dissection of its structure ; for which purpose pow- 

 erful magnifying glasses are frequently necessary. If we 

 wish to ascertain the existence of the integument jx)ssessing 

 the nature of the calyx, we must observe the continuation of 

 the epidermis with its slits in tliat integument, (S\2.) A 

 glandular and fleshy stnicture determines respecting the na- 

 tiu'e of nectaries, as a multitude of short absorbent warlK 

 leads to the belief of {ho existence of the stigma. 



