THE METAZOA 



postpone the inevitable end. Because the 

 supreme fact is that not by physical causes 

 is our stay on earth usually ended. Phys- 

 ical causes may occasionally terminate life 

 by storm, earthquakes or flood, or through 

 human perversity by wars, but aside from 

 such happenings it is by the agency of a 

 great living kingdom that our mortal 

 bodies return dust to dust. 



It is also life which destroys life when 

 death is caused by those dread and well- 

 named malignant diseases, cancer and sar- 

 coma. Never before in medical history 

 has there been such diligent and intelligent 

 search for the origin of these terrible affec- 

 tions as now, until it begins to look as if 

 instead of coming from the old class of 

 unicellular micro-organisms they come 

 from a native metazoan cell which has 

 deserted to the enemy. As with other 

 renegades its greatest hostility is to its old 

 associates, and it is all the more dangerous 

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