VITALITY. 



THE origin, growth, and energies of living things are 

 subjects which have always engaged the attention of think- 

 ing men. To account for them it was usual to assume a 

 special agent, to a great extent free from the limitations 

 observed among the powers of inorganic Nature. This 

 agent was called the vital force ; and, under its influence, 

 plants and animals were supposed to collect their materials 

 and to assume determinate forms. Within the last twenty 

 years, however, our ideas of vital processes have undergone 

 profound modifications ; and the interest, and even dis- 

 quietude, which the change has excited in some minds are 

 amply evidenced by the discussions and protests which are 

 now common regarding the phenomena of vitality. In 

 tracing out these phenomena through all their modifications 

 the most advanced philosophers of the present day declare 

 that they ultimately arrive at a single source of power, 

 from which all vital energy is derived ; and the disquieting 

 circumstance is that this source is not the direct fiat of a 

 supernatural agent, but a reservoir of what, if we do not 

 accept the creed of Zoroaster, must be regarded as inor- 

 ganic force. In short, it is considered as proved that all 

 the energy which we derive from plants and animals is 

 drawn from the sun. 



A few years ago, when the sun was affirmed to be the 

 source of life, nine out of ten of those who are alarmed by 

 the form which this assertion has latterly assumed, would 

 have assented, in a general way, to its correctness,. Their 

 assent, however, was more poetical than scientific, and they 



