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. 
Sporozoax and Bacterial Parasitism in 
Geological History 
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 1 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. 
