TEACHING PARASITOEOGY 
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require magnification to determine, should be looked upon as be- 
longing strictly to parasitology. Local conditions as they exist in 
the various institutions might logically call for some variation in 
this regard. 
MORPHOLOGY 
The work in parasitology should familiarize the student with 
the morphology of the adult parasite including external and 
internal structures, emphasizing such external markings as size, 
structure and any others that will be useful in the identi- 
fication of the parasite. Morphology should further include the 
organs of reproduction, eggs, or ova, embryos, larval and pupa 
forms, as well as the adult. In fact any markings or structures, 
including all stages of development characteristic of different 
forms, that would in any way be of value in identifying the para- 
site or form of parasitism and that have a bearing on methods of 
control, should be included. 
LIFE HISTORY 
Since the control and eradication of animal parasites is largely 
a matter of prevention, it is essential that the student be familiar 
with every phase of the life history including the atmospheric and 
climatic conditions and geographical and geological formations 
favorable to its existence, continuation and spread. In taking up 
the life history of parasites we should start with the eggs, ova, 
and embryos as they are formed or as they leave the adult, and 
trace them through their various stages of development and 
migrations as far as these are known until they have reached the 
host of the mature parasite and are again producing new generat- 
tions. We must impress upon the student the fact that the great 
advantage in combating certain parasites and often the only pos- 
sible way to success is to direct our efforts at the stage of develop- 
ment most susceptible to destruction, and that successfully and in- 
telligently to carry this out we must be familiar with the mor- 
phology of every stage of development and the complete life history 
of the parasite. When we are considering the life history, the fol- 
lowing points will necessarily come up for consideration : 
(a) Is it necessary for the young to leave the host to complete its 
life cycle? 
(b) By what channels and under what conditions are the young 
forms expelled from the body? 
(c) What is the location in Nature? 
(d) Is an intermediate host necessary? 
(e) What is the length of time and the condition under which the 
