SOIL SANITATION 273 



isolated as a germ, but it has been isolated as 

 a toxic substance. Fatigue in muscles of men 

 and animals is not due to a lack of food in the 

 muscles, blood or lymph. It is due rather to 

 an excess of the products of metabolism. ( Soil 

 Fatigue, Oswald Schreiner and M. X. Sul- 

 livan, Jour. Biological Chemistry, Vol. VI.) 



German scientists have been able to isolate 

 a true toxin from the muscles of a tired dog. 

 And, to show that fatigue in this instance 

 was nothing more or less than a poison ex- 

 creted by the muscles in the process of func- 

 tioning, they injected this substance into the 

 muscles of another dog. It brought about all 

 the symptoms of fatigue in the second animal, 

 although that animal was refreshed by a long 

 sleep. 



Thus, when we say a man is tired from 

 breaking stone, we mean that his muscles have 

 accumulated a waste product faster than 

 phagocytes of the blood can carry it away. 

 The action of the muscles becomes sluggish. 

 It is like grit in the bearings of a machine. 



Give the tired laborer rest, sunlight, fresh 

 air let him sleep give the scavengers of the 

 blood time to catch up with their task. Or, 

 change his occupation. Let him do something 



