LESSON VII 

 MOTION AND LOCOMOTION 



1. The Source of Active Power and the Organs of 

 Motion.— In the preceding Lessons the manner in which 

 the incomings of the human body are converted into its 

 outgoings has been explained. It has been seen that new 

 master, in the form of vital and mineral food, is constantly 

 appropriated by the body, to make up for the loss of 

 old matter, which is as constantly going on in the shape, 

 chiefly, of carbonic acid, urea, and water the formation of 

 this waste being the outcome of oxidation accompanied by 

 a liberation of energy. 



The vital foods are derived directly, or indirectly, from 

 the vegetable world : and the products of waste either 

 are such compounds as abound in the mineral world, or 

 immediately decompose into them. Consequently, the 

 human body is the centre of a stream of matter which 

 sets incessantly from the vegetable and mineral worlds 

 into the mineral world again. It may be compared to 

 an eddy in a river, which may retain its shape for an 

 indefinite length of time, though no one particle of the 

 water of the stream remains in it for more than a brief 



period. 



But there is this peculiarity about the human eddy, 

 that a large portion of the particles of matter which flow 

 into it have a much more complex composition than the 

 particles which flow out of it. To speak in what is not 

 altogether a metaphor, the atoms enter the body for the 



