DISEASE GERMS NO T PARASITES. 233 



undoubtedly been shown to be associated with the 

 presence and vigorous growth of organisms belonging 

 to the class of parasites ; but of late the term 

 parasite has been used far too freely, and the word 

 has been employed without due consideration. Not 

 only have the living particles of mucus and pus been 

 thus designated, but the highest living cells in the 

 body of man himself have been called parasites. 



Scientifically speaking, a parasite is an organism 

 which lives upon another organism. The organism 

 does not evolve the parasite any more than the latter 

 produces its host. The organism may live in the 

 absence of the parasite, though for the latter to exist 

 the first is a necessity. The parasite is a descendant 

 of a pre-existing parasite not an emanation from the 

 being upon which, and perhaps by which, it lives. 

 A vegetable or animal organism dependent for sub- 

 sistence upon the juices or secretions of another 

 vegetable or animal organism much higher in the scale 

 is a parasite. But it is as wrong to speak of the con- 

 stituent living growing cells of the human body as 

 parasites, as it would be to assert that the complex 

 individual compounded of them was a parasite. 



Every cell of the organism has been formed by direct 

 descent from the original embryonic mass of bioplasm. 

 The bioplasm of each cell is capable of growth and 

 multiplication, but it cannot be looked upon as para- 

 sitic upon other cells, for its parentage is the same as 

 theirs. For the same reason abnormal cells cannot be 



