4SO THE EVOLUTION OF LIFE. 



appear to stand in the way of this assumption. Ridiculing 

 those who alleged the uniscrial development of organic forms, 

 who, indeed, laid themselves open to ridicule by their many 

 untenable propositions, Von Baer writes " A fish, swimming 

 towards the shore desires to take a walk, but finds his fins 

 useless. They diminish in breadth for want of use, and at 

 the same time elongate. This goes on with children and 

 grandchildren for a few millions of years, and at last who 

 can be astonished that the fins become feet? It is still 

 more natural that the fish in the meadow, finding no water, 

 should gape after air, thereby, in a like period of time 

 developing lungs; the only difficulty being that in the 

 meanwhile, a few generations must manage without breath- 

 ing at all." Though, as thus presented, the belief 

 in a transition looks laughable; and though such deriva- 

 tion of terrestrial vertebrates by direct modification of 

 piscine vertebrates, is untenable; yet we must not conclude 

 that no migrations of the kind alleged can have taken place. 

 The adage that " truth is stranger than fiction," applies quite 

 as much to Nature in general as to human life. Besides the 

 fact that certain fish actually do " take a walk " without any 

 obvious reason; and besides the fact that sundry kinds of 

 fish ramble about on land when prompted by the drying-up of 

 the waters they inhabit ; there is the still more astounding fact 

 that one kind of fish climbs trees. Few things seem more 

 manifestly impossible, than that a water-breathing creature 

 without efficient limbs, should ascend eight or ten feet up the 

 trunk of a palm; and yet the Anabas scandens does as much. 

 To previous testimonies on this point Capt. Mitchell has 

 recently added others. Such remarkable cases of temporary 

 changes of media, will prepare us for conceiving how, under 

 special conditions, permanent changes of media may have 

 taken place; and for considering how the doctrine of evolu- 

 tion is elucidated by them. 



Inhabitants of the sea, of rivers, and of lakes, are many 

 of them left from time to time partially or completely with- 



