ORGANIC DEPENDENCE AND DISEASE 107 



regard this distinction important and essential. It is not 

 easy to ascribe to the former as we now understand it, any 

 other force than a pulsing chemistry. In the parasitic 

 association of metazoans that conception must be wholly 

 put aside; here the association is a mechanical one though 

 governed by a pulsing vitality. It is easy to say that the 

 latter is naturally a derivative of the former, much less 

 easy to show evidence for the assumption. The latter is 

 probably successive in time to the former but we cannot 

 show that it exists because of the former. 



The course of protoplastic parasitism is essentially chem- 

 ical and so when it is really pathologic, chemical neutraliza- 

 tion is the accepted practice. But the procedure in destroy- 

 ing the bacillus of tetanus is of an altogether different code 

 from the procedure for the destruction of chigoes, tapeworm 

 or trichina. The "attack," or speaking with exactitude, 

 the adjustment of the sporozoan parasite, is, as we have 

 stated, an invasion of the molecular contents of the cell and 

 an absorption of its protein ; in the metazoan parasite the 

 attack involves an ablation or readjustment of organs or 

 organized tissue. 



Spoeozoan and Bacteeial Paeasitism iisr 

 Geological Histoey 



There are pretty clear evidences of the activity of epi- 

 demic infections in geological history and there are, besides 

 these, occurrences which have suggested such interpretation 

 but which may be open to other construction. We have the 

 word of such botanical specialists as Massee^ and Berry 

 that even in Carboniferous times the plant world had be- 

 come infested with parasitic fungi, a fact which of itself 

 bespeaks a long development leading up to these adjust- 

 ments. 



1 Massee speaks of four hundred species of such parasitic Carboniferous 

 fungi. 



