566 
G. L. BUFFINGTON. 
of two organisms with more or less constancy, various modi¬ 
fications of form and function must occur. In some of the 
lower forms of animal life, where the host is but little higher 
than the parasite which infests it, the latter sometimes has a 
mechanical transforming effect on the host without seriously 
interfering with its function. In the higher animal, however, 
the effects on the host are more serious and more markedly 
pathological. 
Leuckart distinguishes pathological effects as due either to 
growth and increase of parasites, to their wanderings within 
the body or to the very considerable loss of nourishment 
which a number of parasites of appreciable size necessarily 
entails. The mechanical effects also are often of a serious na¬ 
ture. Thus parasitic worms by their size or number some¬ 
times close up passages, as blood vessels or the bronchial tubes, 
often causing fatal results. 
According to the old hypothesis, the pathological state of 
the host was not the result of the parasite, but was the cause, 
and in fact created them. And in spite of the gradual un¬ 
ravelling of the mysteries of origin and life-history, medical 
men clung conservatively to the old hypothesis of spontaneous 
generating. The ingenious experiments of Pasteur have, how¬ 
ever, prevailed against all refractory opposition, and peremp¬ 
torily established the fact that spontaneous generation could 
not be invoked even for the infinitely small parasites or mi¬ 
crobes. So it is not until within the last fifty years, that with 
the rise of experimental helminthology, medical science 
shook itself free from superstition and ignorance and devoted 
close attention to etiology and treatment, culminating in that 
systematic warfare against all forms of parasitism which now 
occupies so important a place in medical and veterinary sci¬ 
ence. 
During the winter of ’9i-’92 my attention was for the first 
time directed to the serious nature of parasitism and the un¬ 
wonted loss some of these small animal organisms may cause. 
No other one disease has caused so much loss, during the past 
year, among colts in the country in which I reside, as (hat 
caused by intestinal parasites, and that mostly by the scleros- 
