174 THE LIFE OF THE FIELDS. 



since an experiment was tried with a jack, an account 

 of which appeared in the papers. The jack was in a 

 tank, and after awhile the tank was partly divided by 

 inserting a plate of glass. He was then hunted round, 

 and notes taken of the number of times he bumped his 

 head against the plate of glass, and how long it took 

 him to learn that there was something to obstruct his 

 path. Further statistics were kept as to the length of 

 his memory when he had learnt the existence of the 

 glass — that is, to see if he would recollect it several 

 days afterwards. The fish was some time learning the 

 position of the glass ; and then, if much alarmed, he 

 would forget its position and dash against it. But he 

 did learn it, and retained his memory some while. It 

 seems to me that this was a very hard and unfair test. 

 The jack had to acquire the idea of something trans- 

 parent, and yet hard as wood. A moment's thought 

 will show how exactly opposite the qualities of glass 

 are to anything either this particular fish or his 

 ancestors could have met with — no hereditary intelli- 

 gence to aid him, no experience bearing, however 

 slightly, upon the subject. 



Accustomed all his life to tranparent water, he 

 had also been accustomed to find it liquid, and easily 

 parted. Put suddenly face to face with the trans- 

 parent material which repelled him, what was he to 

 think ? Much the same effect would be produced if 

 you or I, having been accustomed, of course, all our 

 lives, to the fluidity of air, which opens for our 

 passage, were opposed by a solid block of transparent 

 atmosphere. Imagine any one running for a train, 

 and strikinoj his head with all his misfht ao^ainst such 



