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3. Therapeusis. 
This phase of the subject has not been prosecuted as 
vigorously as the preceding phases. The birds have only 
recently become available for experiment through the 
systematic examination and most time was demanded in 
this latter direction and for work on life history. 
Theoretically the prospect of a successful therapy is 
not bright. The worms live in the soft juicy wall of a 
canal between the crop and gizzard. Sometimes they 
appear in the lumen of this canal, in which case they are 
always surrounded by thick, tenacious mucus. If they 
are pulled out of this with forceps and are laid on the 
mucus they at once bore into it. It protects them from 
any passing medicament. This medicament, too, is apt 
to have only a transient effect while on its way from the 
crop to gizzard. Those worms which may be partly 
protruded into the lumen from the wall of the canal can 
retract and retreat, even as far as the serosa, as shown 
in one of our museum specimens. The smallest worms 
are found under the thick, chitinous lining of the gizzard. 
It may be necessary, therefore, to use drugs both in 
the lumen (drugs by mouth) and by way of the blood 
(hypodermically) . So far thymol and arsenic have been 
used. 
Preliminary work on pigeons showed the lethal dose of 
thymol, suspended in mucilage of acacia to be four 
grains. Half this dose was given to golden-naped 
Amazon whose stools showed numerous ova. The drug 
is squirted into crop through a catheter attached to a 
syringe, the catheter being passed through a hole in a 
block of wood which wedges the birds beak apart. In 
this way we are sure of administering the full dose, and 
that none enters the trachea. This dose caused no 
alarming symptoms. Ova could still be found in stool 
but in reduced numbers. The dose was increased at five- 
day intervals to six grains. The ova were still present in 
the stools. With the idea of absorption of the drug into 
the blood, the thymol has since been suspended in 
