Diseases of Poultry. 
195 
the trachea, or in which the disease is propagated, for a long time remained mysterious. I he 
missing link was of course the history of the egg and its development, till the time when it is found, 
fully matured, in the infected chicken. M. Megnin states, in a prize essay on the subject, that the 
eggs never hatch within the living body of the parent, however mature ; but that after her death, 
or in any other circumstances where they have damp and a temperature of not less than 68° Fahr., 
they hatch. They will thus hatch in moderately tepid water, and will live for nearly a year in 
water, if kept at the requisite temperature. Hence he concludes that no host or bearer is necessary, 
and that all such have been unjustly suspected. 
It is, indeed, probable that pond water may be in numerous cases the medium of infection. 
But the statement that no intermediate host or bearer is concerned, as in so many other 
parasites, is disproved. Mr. A. M. Halsted, of Rye, New York, writes as follows — 
“ A number of years ago, in examining some young chicks just taken from the nest, 1 
noticed on the head some large insects (Fig. 55). I found the head of the insect was embedded in 
the skin of the chick’s head, and so deeply that when I pulled them off the 
chick would cry out in pain. I have found from two to a dozen on a single 
chicken. I took the pains to pick all these insects off the heads of that 
brood, and examined them every few days until six weeks or more old, 
removing what few ticks made their appearance after the first operation. I 
did not follow it up in other broods, removing these more as an experiment, 
to see what would follow. As the season advanced our chickens commenced 
to die off with the gapes. Some entire broods died, others in part ; but of 
this brood I did not lose one chick. The next season I resolved to try it on 
a larger scale, but found the picking-off insects a tedious operation. I tried 
application of cold grease to the head, but it would not answer. Then tried 
mercurial ointment, and killed a good many of the little chicks ; then kerosene 
oil, with a like result ; next melted lard, and was partially successful with that ; still I had 
a few cases among those anointed. Finally, I compounded an ointment of : — Mercurial ointment 
(the weaker kind), 1 oz. ; pure lard, 1 'oz. ; flour of sulphur, oz. ; crude petroleum, 5 oz. This is 
applied to the head of the chick in a melted or semi-fluid state ; and now for six years I have 
not lost a chicken when the ointment has been applied at the time of taking the chickens from 
the nest. I have had friends try the same experiment in yards where they were troubled 
with the gapes, with nearly the same result. 
“ It is well known that on all animals that do not perspire the parasites that infest the body 
make their way to the nostrils to drink. And in some cases (sheep for one, it is stated) the 
parasite either penetrates the nostril and there deposits its egg, or deposits it at the opening 
of the nostril, and it is conveyed back by natural causes. This egg in time becomes a larva 
or worm, and causes disease. In the chicken the worm follows the nostril back until it reaches 
the opening of the trachea, and there makes a lodgment ; as they grow they gradually fill the 
opening, and thus produce the gasping for breath consequent upon partial suffocation, which is 
called the gapes. It seems possible that the disease is transmitted the same as the bot-flv; 
the ‘ tracheal-worm,’ on the death of the chicken, finding its way into the earth, and reproducing 
itself in the form of the tick, or perhaps fly.” 
Any such theory as this, in the precise form adopted by Mr. Halsted, is of course utterly 
untenable. The louse is a perfect insect, the egg and young of which are known : while the co-o- 
of the gape-worm is also known, and has been figured by microscopists. But it seems probable 
that the large insect or louse may serve as the host or vehicle for conveying either the ova or the 
