PECULIAR OfLaANIZATIONS. IQ6 



IS found in land- animals ; and a life in the water has no 

 natural tendency to produce a bag of air. Nothing can bo 

 further from an acquired organization than this is. 



These examples mark the attention of the Creator to the 

 three great kingdoms of his animal creation, and to their 

 constitution as such. The example which stands next in 

 point of generality, belonging to a large tribe of animals, or 

 rather to various species of that tribe, is the poisonous tooth 

 of serpents. 



I. The fa?ig of a vijoer'^ is a clear and curious example 

 of mechanical contrivance. It is a perforated tooth, loose 

 at the root ; in its quiet state lying down flat upon the jaw, 

 but furnished with a muscle, which, with a jerk, and by the 

 pluck as it were of a string, suddenly erects it. Under the 

 tooth, close to its root, and communicating with the perfora- 

 tion, lies a small bag containing the venom. When the 

 fang is raised, the closing of the jaw presses its root against 

 the bag underneath ; and the force of this compression sends 

 out the fluid with a considerable impetus through the tube 

 in the middle of the tooth. What more unequivocal or 

 effectual apparatus could be devised for the double purpose 

 of at once inflicting the wound and injecting the poison ? 

 Yet, though lodged in the mouth, it is so constituted, as, in 

 its inoffensive and quiescent state, not to mterfere with the 

 animal's ordinary office of receiving its food. It has been 

 observed also, that none of the harmless serpents, the black 

 snake, the blind worm, etc., have these fangs, but teeth of an 

 equal size : not movable as this is, but fixed into the jaw. 



II. In being the property of several difierent species, the 

 preceding example is resembled by that which I shall next 

 mention, which is the bag of the ojjossum.f This is a me- 

 chanical contrivance, most properly so called. The simpli- 

 city of the expedient renders the contrivance more obvious 

 than many others, and by no means less certain. A false 

 skin under the belly of the animal forms a pouch, into which 



* Plate IV., Fig. 2, and 3. t Plate IV., Fig. 4 



