THE EXPLODED GHOST CALLED CALORIC 397 



insist on the older barbaric "explanations" of these 

 marvels. Few indeed venture to assert the existence of 

 "spirits" — ghostly essences of various grades and capacities 

 which enter the bodies of living things and escape from 

 them like so much gas when they die.* The vegetable 

 soul, the animal soul and the human soul are no longer 

 imagined and described to us as definite "things" sup- 

 posed to " explain " the complex processes which go 

 on respectively in plants, animals and men. 



Seventy years ago the facts which were known as to that 

 changing state of material substances which we describe by 

 the words "hot" and "cold," were held to be "explained" 

 by the existence of a ghostly thing called "caloric," which 

 was believed to enter various bodies and make them 

 hot and then to escape from them and so make them 

 cold. Primitive man multiplied such ways of explaining 

 each and every process going on in the world around him 

 and in himself. Mere words or names lost their first 

 simple signification and acquired permanent association 

 with imaginary spirits, demons, and haunting intangible 

 ghosts, by reference to which our ancestors in their earliest 

 " reasoning " explained to their own satisfaction the 

 strange and sudden events fraught to them with .the daily 

 experience of pain or pleasure. The whole world was held 

 by them to be " bewitched," and it was only by slow and 

 painful steps that some knowledge of the persistent order 

 of Nature was obtained, whilst the phantastic imagery 

 which had served in its place, bit by bit disappeared. 

 " Caloric " was a late lingerer, and was only got rid of 



• This subject is discussed and some account of the chemical nature of 

 protoplasm given in my book, ' Science from an Easy Chair ' (Methueii, 

 1910), which consists of a first series of papers similar to those which are 

 collecteil in the present volume as a " Second Series." The chapters in 

 the earlier volume to which I wish to direct the reader's attention are those 

 entitled " The Universal Structure of Living Things," " Protoplasm, Life 

 and Death," "Chemistry and Protoplasm," "The Simplest Living Things." 



