STUDIES IN ANIMAL LIFE. 61 



carefiilly put aside wlaere its surface can. not be dis- 

 turbed. If a sheet of paper on which a key has 

 been laid be exposed for some minutes to the sun- 

 shine, and then instantaneously viewed in the dark, 

 the key being removed, a fading spectre of the key 

 will be visible. Let this paper be put aside for 

 many months where nothing can disturb it, and 

 then in darkness be laid on a plate of hot metal, 

 the spectre of the key will again appear. In the 

 case of bodies more highly phosphorescent than 

 paper, the spectres of many different objects which 

 may have been laid on in succession will, on warm- 

 ing, emerge in their proper order.* 



This is equally true of our bodies and our minds. 

 We are involved in the universal metamorphosis. 

 Nothing leaves us wholly as it found us. Every 

 man we meet, every book we read, every picture 

 or landscape we see, every word or tone we hear, 

 mingles with our being and modifies it. There are 

 cases on record of ignorant women, in states of in- 

 sanity, uttering Greek and Hebrew phrases, which 

 in past years they had heard their masters utter, 

 without, of course, comprehending them. These 

 tones had long been forgotten; the traces were so 

 faint that under ordinary conditions they were in- 

 visible ; but the traces were there, and in the in- 

 tense light of cerebral excitement they started into 

 prominence, just as the spectral image of the key 

 started into sight on the application of heat. It is 

 * Draper : Human Physiology, p. 288. 



