Life Among Parasitic Animals 41 
PRESIDENT’S ADDRESS. 
THE PROBLEMS OF LIFE AMONG PARASITIC ANIMALS. 
Howard E. Enders. 
The development of parasitology as a special phase of zoology has 
been made possible through a recognition of its economic applications 
in agriculture, horticulture, veterinary medicine and public health. The 
applications in medicine and public health help to re-establish the close 
relationship to the science of medicine from which zoology originally 
developed into the importance of a separate science. 
Need for the further development of the field of parasitology was 
thoroughly emphasized in the recent war, through the work accomplished 
by the parasitologists of the Sanitary Corps in eradication of the lice, 
which became active agents in the spread of typhus and trench fevers 
that levied a heavy toll throughout all of Serbia and more or less else- 
where. Before the war few colleges offered courses in this work but 
with the return of men to the educational duties new courses were under- 
taken and the older courses were given new life and renewed activities 
in a field in which so much remains to be investigated. 
A generation or two ago, when the presence of amiable flies about 
the table was a token of the hospitality and general kindliness of the 
hostess, the louse and the flea and other more or less personal attendants 
were regarded at most only as petty annoyances. Most of these forms 
are now regarded as parasites. In its original use the term “parasite” 
was employed to describe those who sat about the tables of the rich of 
ancient Greece, by virtue of their fawning and flattery. It does not 
require a wide stretch of the imagination to understand how a similar 
relation was ascribed to the animals which lived upon other animals 
and there maintained a thievish existence at the expense of the host. 
How they came into being, or how they came to be where they were 
was as readily accounted for as was the origin of Topsy, in “Uncle Tom’s 
Cabin”, and each had as real a purpose in life as was expressed by 
“David Harum” of the fleas: “A reasonable amount of fleas is good for 
a dog; it keeps him from brooding over being a dog.” 
The idea that life could spring suddenly into existence made it as 
readily possible to account for the origin of any parasite within or 
upon a host, as for the host itself. The belief in the spontaneous origin 
of parasites and “other vermin” from filth or other “formative ma- 
terials”, was so firmly held that formulas were given for the production 
of certain forms of life, and to doubt it was to question reason and truth. 
Development within the field of biology in a period possibly only 
a little longer than the lifetime of the oldest person here, has been made 
possible through the epoch-making discovery of protoplasm as the phys- 
ical basis of life; the formulation of the cell-theory; the exposition of 
the theory of evolution of plants and animals; the development of the 
