348 PAPILLA? OF FROG'S TONGUE 



drawn as regards the question of Design from a careful and 

 minute examination of the structural arrangements of any 

 delicate organ. Let us take, for example, one of the sim- 

 plest, such as a little papilla or elevation projecting from 

 the general surface, or one of the beautiful but more com- 

 plex papillae from the tongue of the frog, such as I have 

 figured in Plate XV, and the structure of which has been 

 already briefly described in page 256. 



Any one who carefully studies this apparatus, exhibit- 

 ing sensitive and motor functions, which projects from the 

 general surface of the tongue, will, I think, find it difficult to 

 believe that the organ has not been constructed for a definite 

 purpose, or that its action is only an accidental result of 

 its existence. 



It happens that there are some delicate striped muscular 

 fibres, with a complex system of nerves, so arranged that 

 when anything touches the summit of the papilla it is short- 

 ened and retracted, and the delicate nerve organ may some- 

 times in this way be saved from impending injury. Is the 

 apparently purposive arrangement resulting from a long 

 series of orderly and complex changes a mere accident, 

 or can the structures, their arrangement and action, be 

 accounted for by the properties of the substances entering 

 into the composition of the tissues of the papilla ? It is use- 

 less to assert that the arrangement has been brought about 

 by law, unless the laws are known, and can be defined. 



The bundle of sensitive nerve fibres occupies the very 

 centre of the papilla, and near the summit every one of 

 these fibres divides and subdivides, and the branches break 

 up to form a wonderful plexus, from which still more minute 

 fibres pass to the organ situated upon the summit of the 



