An Introduction to a Biology 



once or twice again, but there was nothing to be done, and at 

 last the morning came. On my departure from the ship my 

 courage failed me, and I did not leave instructions "\vith the 

 ship's carpenter. But it may be imagined that I lost no 

 time in writing to my friend in Naples, telhng him of all 

 this, and asking him whether I had left him one or two 

 toads, for I knew that I had brought six from Ischia, and 

 that his answer would settle the question whether or not 

 I had left the cabin tenanted. 



* In about a week I heard from him. " Set your mind at 

 rest : you left me two." 



I can, of course, only guess what the noise was. But 

 the fact that I did not hear it until my companion joined 

 the ship, a circumstance which I attributed at the time to 

 the absence of any occasion for the kind of anxiety that I 

 felt after he had arrived ; the fact that I heard it each night 

 for the first time an hour or so after retiring to rest ; the 

 fact that I first definitely located it under my companion's 

 berth and then in it, and, moreover, that it always followed 

 a movement of restlessness on his part, point to the conclu- 

 sions that it was effected either gutturally by him or by 

 a grinding of his teeth. 



But the two points I wish you to notice about this are 

 these. First, that having started with the not unreason- 

 able idea that a toad had escaped, I spent those long nights 

 in weighing the value of every possible piece of evidence 

 that could conceivably bear on it, and in making every possible 

 experimental test of every interpretation of the phenomenon 

 that occurred to me ; and that the more I weighed evidence 

 and devised experiment, the less did I question the reality 

 of the very thing that I was trying to find out. I started 

 by trying to find out whether a toad had escaped ; I ended 

 by endeavouring to discover what, since it had escaped, it 

 was actually doing. And if you will look back over the 

 details of the story, you will see how gradual the transition 

 from one stage to another was. 



256 



