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THE LIBRARY

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THE UNIVERSITY

OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND

MRS. PRUDENCE W. KOFOID

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THE

Gape Worm of Fowls

( Syngamus trachealis );

(Lumbricas terrestris),

ITS INTERMEDIATE HOST.

ALSO,

On the Prevention of the Disease in

Fowls called the Gapes, which

is Caused by this Parasite.

i%V

OEOID,

=7= RY,

U [> ■

BY

FRANKL1NVILLE, N. Y.

THE

Gape Worm of Fowls

(Syngamus trachealis);

THE KARTHWORM

{Lumbricus terrestris),
ITS INTERMEDIATE HOST.

ALSO,

On the Prevention of the Disease in Fowls

Called the Gapes, which is Caused

by this Parasite.

By H. D. WALKER, M. D.,

FRANKLINVILLE, N. Y.

COPYRIGHTED BY

DR. H. D. WALKER, Franklinville, N. Y.,

AND

J. Y. BICKNELL, Buffalo, N. Y.
189 7.

SYNGAMUS TRACHEALIS.

EXPLANATION OP FIGURES.

Fig. 1— Adult, male and female Syngamus, united (natural size and enlarged 12 diameters).
A, male; B, female, each showing the head, esophagus and intestine. In the female
may be seen the uterus and ovarian tubes filled with eggs. In the male, the seineniferous

tube.

Fig. 2.— Smallest pair of Syngami ever seen (enlarged 50 diameters). A, male; B, female.

Fig. 3.— Embryo of Syngamus removed from the earthworm and kept in the blood serum of
a calf, in an incubator, at 105° Fahr., between four and five days. About moulting the
second time after being placed in the serum. Embryo lying within the exuviae. See
structure of mouth of embryo, and also in the exuviae (enlarged 200 diameters).

Fig. 4.— Embryo of Syngamus removed from the earth worm and kept in the blood serum of
a calf, in an incubator, at 105° Fahr., for 24 hours. About moulting the first time after
being placed in the serum (enlarged 200 diameters).

Fig. 5.— Embryo of Syngamus removed from the lung of a chick fed earthworms containing
the embryos. This embryo had just entered the lung (enlarged 200 diameters).

/7„ 6.— Embryo of Syngamus removed from the intestinal canal of an earthworm (enlarged
200 diameters).

jJ7ff- 7.— Embryo of Syngamus within the egg < enlarged 200 diameters).

Fig. 8.— Egg of Syngamus in the mulberry state (enlarged 2li0 diameters).

jrtc,. <». — Perfect egg of Syngamus immediately after passing out of adult female (enlarged
200 diameters).

/,•,„_ id— Caudal pouch of male. Observe the eight principal ribs which are subdivided SO
there are eighteen divisions at the circumference, each extremity of which i> expanded
into a sucker. These suckers project through the broad margin of the pouch which is
closely applied around the vulva of the female, to which they enable it very firmly to
adhere. The posterior part of the circumference of the pouch is cut out and has no suck-
ers. Here is where the eggs pass out.

15354637

PREFACE.

Fourteen years having- elapsed since I first commenced the
study of the gapes in fowls, it cannot be asserted that the con-
clusions now arrived at are hasty and have not stood the test
of time and mature consideration. My first paper on the sub-
ject was read before the Buffalo Microscopical Club, November
nth, 1884. In 1886 I published a paper in the Bulletin of the
Buffalo Society of Natural Sciences, Vol. V., No. 2. The pres-
ent publication is a revision of that paper, with extracts from
articles written for various journals, and additional matter here-
tofore unpublished in regard to the life history of the parasite
causing the gapes. The illustrations are from drawings made
by Mrs. Helen M. Judd from microscopic slides. I send forth
this small pamphlet with the earnest desire that science and the
poultry and game bird raisers throughout the world may be

benefitted thereby.

H. D. WALKER.
Franklinville, N. Y., November, 1897.

INTRODUCTION.

In the following pages we present the results of experiments
made for the purpose of determining the intermediate host of
the gape worm of fowls. We have endeavored at the same time
to trace out the life history of this parasite, in its various stages
from the egg to the perfect worm, also to devise means for the
prevention of the disease caused by it among fowls.

The object of undertaking the work was two-fold. First, it
was thought if its intermediate host could be discovered the
disease might be prevented to a great degree, and much good
result therefrom. Second, the love of original investigation and
a determination to work out the life history of this parasite,
which, although well known in its mature condition in the
trachea of fowls for about one hundred years, had thus far, in its
embryonic state in nature, remained unknown. The work has
been exceedingly difficult, for several reasons. When the inves-
tigation was begun, I knew nothing about Entozoa. Microscop-
ical work was also comparatively new. Living in a small vil-
lage, I had no public libraries to consult, and was dependent for
the literature of the Entozoa on a few books which I procured
during the investigation. My profession also left me little leisure,
and the most of this work has been done at such odd times as I
could spare from other duties. I wish here to express my thanks
to that eminent naturalist, the late Dr. Joseph Leidy, of Phila-
delphia, for many favors in inspecting my microscopic slides, and
for advice and encouragement in the work. Valuable, indeed,
were the services he rendered me. I am under obligations to
Lord Walsingham, of England, for books to aid in the investi-
gation. Friends in the Buffalo Microscopical Club, and neigh-
bors have also assisted me in various ways. I have freely con-
sulted Dr. T. Spencer Cobbold's work on "Parasites," also Pro-
fessor L. G. Neumann's treatise on "Parasites and Parasitic Dis-
eases of Domesticated Animals," and Dr. Pierre Megnin, "On
the Gapes Disease in Gallinaceous Birds." Finally, I trust these
pages will not be scanned with too critical an eye, for, doubtless,
imperfections will be found. I can only say that I have honestly
endeavored, according to the best of my ability, to place before
the reader the life history of one of the humblest of creatures, a
worm, but which, nevertheless, plays well its own part in this
world of animated nature.

ZOOLOGICAL CLASSIFICATION AND HABITAT.

The Animal Kingdom is divided into several sub-kingdoms.
One of these is called Worms (Vermes). This sub-kingdom is
separated into classes, one of which is named Round Worms
(Ncmatliclminths). Another division into orders is made, among
which are the Nematode Worms (Nematodes). This order con-
tains, among other genera, that of Syngamus, which is repre-
sented by two species, Syngamus bronchialis and Syngamus
trachcalis, the last of which is the subject of our present work.*

Another name for this worm is Sclcrostoma, or Strongylus
syngamus. Syngamus trachcalis is stated to have been found in
the trachea of the turkey, domestic fowl, pheasant, partridge,
black stork, magpie, hooded crow, green woodpecker and star-
ling. I have, myself, found it in the robin, and believe most if

not all worm-eating birds serve as a host for this parasite.
■*
HISTORICAL REFERENCE.

The first public record of the Gapes was made by Dr. Wiesen-
thall, Professor of Anatomy at Baltimore, Md. In a communica-
tion dated May 21st, < 1797, and published in the Medical and
Physical Journal in 1799, he says: "There is a disease prevalent
among the gallinaceous poultry in this country called the gapes,
which destroys eight-tenths of our fowls in many parts, and is
most prevalent among young turkeys and chickens bred upon
established farms. Chicks and poults, in a few days after they
are hatched, are frequently found to open wide their mouths
and gasp for breath, at the same time sneezing and attempting
to swallow. At first the affection is slight, but gradually becomes
more and more oppressive, and ultimately destroys; very few
recover; they languish, grow dispirited, droop and die. It is
generally known that these symptoms are occasioned by worms
in the trachea. I have seen the whole windpipe completely filled
with these worms, and have been astonished at the animal's being
capable of respiration under such circumstances." The above
is a truthful description of the disease as it prevails in this coun-
try to-day. In 1808, Mr. George Montagu gave an account to
the Wernerian Society of a species of Fasciola. which infests
the trachea of poultry, with a mode of cure. This led to its being
noticed in the systematic works of the day. Dr. Cobbold, from

•The aame of the genus Syngamus is derived from two Greet words, o » 0, with, together,

andy«uo«, marriage, and 1ms icl'ercnee In the peculiar union of the sexes.

whose work on parasites this brief history was taken, has made
some observations on this worm. In 1879, Lord Walsingham,
of England, offered a prize of two hundred and fifty dollars, to
be awarded by the Council of the Entomolpgical Society of Lon-
don, for the best essay, comprising a complete life history of
the parasite causing the gapes. Mr. Charles Black and Dr.
Pierre Megnin, a well-known French scientist, competed for the
prize. The latter received the award. The conclusions at which
he arrived in regard to the propagation of the disease are as fol-
lows: First, that birds pick up mature Syn garni filled with eggs,
which are coughed out by those having the disease, or the eggs
are taken in their food, or the embryos after they are hatched in
water, and they are developed within them to the perfect form.
Second, that no intermediate host, as perfect insects, larvae, mol-
lusks, or any other living agent, has any share in spreading the
disease. In a supplement to the above, after discovering a
nymph of Syngamus in the pulmonary tissue of a red partridge,
he says: "In the preceding memoir, written about twenty months
ago, we pointed out that the eggs ejected during the coughing
fits hatch in the water, and that the embryo, resembling an
anguillula, may live in this medium for many months, because
we have kept some alive almost a year, in a low temperature.
The birds are infected by drinking the water containing these
embryos. But how are they developed in the body of birds,
and in what way do they reach the trachea, where they are found
in the adult stage, fixed to the mucous membrane, like leeches,
the two sexes united in a permanent manner, and the females
crowded with eggs?" He closes the supplement as follows:
"This discovery of the nymph enables us to say that all the
developmental phases of Syngamus trachealis are now known.
The only two media which this parasite inhabits during its entire
existence are the water or moist earth during its embryonal con-
dition, and the respiratory organs of its victim during its nymphal
and its adult phase. It is developed without the aid of any other
medium than the water, corresponding in this respect to the im-
mense majority of verminous parasites." This, then, is the con-
clusion at which Dr. Megnin arrives, after five or six years' study
of the gapes in the various pheasantries of Central France, and
around Paris. Dr. Cobbold says, in his work on "Parasites,"
page 445: "A change of hosts is probably necessary, but in the
first instance they either enter the substance of fungi or other

8

vegetable matters, or they bury themselves in the soil a short
distance from the surface." In Lord Walsingham's preface to
the essay by Dr. Megnin, he says: "By Dr. Megnin's permis-
sion, his memoir is now published in a separate form, the sub-
ject of it being one which could not rightly be included amongst
the publications' of the Entomological Society, although at the
time of offering the prize I was led, by information gathered from
various sources, to think it possible that the larvae of some insect
acted the part of host to the embryonic form of Syngamus." Dr.
Joseph Leidy believed the embryos would be found in some in-
termediate host. The above comprised our knowledge on the
subject when this research was begun.

PRESENT INVESTIGATION.

The present investigation was commenced during the summer
of 1883. Great numbers of young poultry dying of the gapes,
some of my neighbors applied to me for aid to arrest the disease.
Knowing very little about the gapes, but having heard it was
caused by worms in the trachea, I made a careful examination
of their windpipes, and found numbers of the worms attached
thereto by their sucker-like mouths. Never having studied the
Entozoa, and having no works on them, I sent a specimen to
Dr. Joseph Leidy, of Philadelphia, asking him its name, and
where I would find information on the subject. He kindly re-
plied, and referred me to Dr. Cobbold on "Parasites," and an
article by Dr. N. H. Paaren, in the American Entomologist, Vol.
2, page 149. I immediately procured these, and reading the ar-
ticles on that subject, could find nothing regarding its origin.
I therefore again addressed Dr. Leidy, asking him for the de-
sired information. On August 15th, 1883, I received his reply
as follows: "The source of the gape worm (Syngamus trachealis),
of chickens, has not been discovered. If you have an opportunity
of investigating and determining its origin, you may do much
service to science. It would be found only in the embryonic
or larval condition, in some intermediate host." I thought this
was not only a good field for microscopic examination, but also
one which, should I succeed in the work, would be productive
of much good. Therefore, I commenced an investigation of the
coops and their vicinity, where the chicks suffered must from the
gapes. About these I found three not improbable sources of the
disease: First, the common earth worm (I.iimbriats terrestrls) ;

9

second, the sow bug (Oniscus ascllus); third, the garden slug
Limax Havus). My attention was especially directed to one coop
where the chicks all had the gapes. This was placed on a grassy
plot, but close by its side was a small space of bare ground, a
few inches square. It seemed quite probable that here was the
place where they obtained the parasite, so I dug into it and found
it full of earthworms. I took some of these home and exam-
ined them with the microscope, as I did also Oniscus and Limax.
I found that both the slug and earthworm contained various
kinds of parasites in abundance. None were found in Oniscus.
To determine which one, if any of these, was the intermediate
host of Syngamus trachcalis, I procured some young chicks from
a neighborhood where no gapes existed, and fed each separately
to the chicks. In neither of the chicks fed with sow bugs or
slugs was any result produced, but the chick fed with earth-
worms developed symptoms of the gapes. To guard against
error, all the chicks were kept in a barn where they had no access
to the ground, and their food was cornmeal mixed with pure
water.

EXPERIMENTS IN FEEDING EARTHWORMS.

Exp. i. On September 29th, 1883, at 8:30 a. m., a marked
chick, about one week old, was fed ten earthworms from the bare
spot of ground by the side of the coop where the chicks had
the gapes. The worms were carefully washed in water to re-
move all the dirt adhering to them, which might contain the
eggs or embryos of Syngamus. On October 6th, at 7:30 a. m.,
six days and twenty-three hours after the feeding, I observed the
first symptoms of the gapes. On October 7th, at 10:30 a. m.,
eight days and two hours after feeding the chick, and twenty-
seven hours after the first symptoms of the disease, I killed it and
found twenty-six gape worms. Of these worms, two only were
found in the trachea; they were at its upper part, and were the
largest. Ten or twelve of them were in the pharynx. The re-
mainder were in the esophagus, from its upper part half way
down to the crop. All these were united in pairs, except one
male and female.

Exp. 2. On October gth, at 8 a. m., another chick, a little
over two weeks old, was fed four earthworms from the same
place, with like precautions. At the same time of day on the
10th it was fed six worms. On the nth, 12th, 13th, 14th and

IO

15th it was fed ten worms daily. At the same time from the first
feeding, a little less than seven days, it had the gapes. It was
killed in eight days and twelve gape worms found, all in the
trachea.

Exp. 3. November 13th three chicks, two days old, were fed
earth worms from my garden, eight, nine and ten days, respect-
ively. No symptoms of the gapes were produced, but to deter-
mine positively, the one fed nine days was killed, and no gape
worms found. This experiment shows that all earthworms do
not contain the embryo of Syngamus. To confirm this, earth-
worms from the same place have been repeatedly examined with
the microscope, and none of the embryos found.

Exp. 4. Two mature Syngami were broken in pieces, so as
to free the eggs. They were then placed on the surface of a dish
filled with dirt, well moistened with water. After two weeks
some earthworms were placed in this dish and allowed to remain
ten days. Three of these were fed to a chick, which was care-
fully watched for two weeks. No symptoms of gapes were dis-
covered. Evidently the embryos had not obtained access to
the earthworms in sufficient numbers to produce the disease in
chicks.

Exps. 5 and 6. On December 13th, two chicks, four weeks
and four days old, were each fed six earthworms from the infected
spot, with the same precautions as before. On the 14th, 15th
and 1 6th the feeding of six worms was repeated, making twenty-
four to each chick. On December 20th, about seven days, as
before, they had the first symptoms of the gapes. One was now
killed, and twenty-two Syngami were found. On December
24th, eleven days from the first feeding, the other was killed, and
sixteen f6und. All of them were united, and in the trachea.
None were found in the lungs, but it is probable they were there,
and want of experience in the search prevented their discovery.

Exps. 7, 8 and 9. On April 21st, 1884, fed three chicks, two
days old, each five worms from the same place where the others
were obtained. Repeated the feeding on April 22d, 23d, 24th,
25th, 26th and 27th. On April 28th, about seven days from the
first feeding, all had the gapes. One was now killed ami Syngami
found in the trachea, also three pairs in the lower part of the left
lung and one pair in the lower part of the right lung. Continued
to feed the two remaining chicks earthworms until May 5th, just
two weeks from the first feeding, when one was killed and the

II

lower part of the trachea found crowded with Syngami. One of
these measured seven-eighths of an inch in length, and two or
three others three-fourths of an inch. They contained fully de-
veloped eggs, as did also the excretions of the chick just before
it was killed. This proves that the embryo of Syngamus in the
earthworm is developed to maturity in two weeks from the time
it obtains entrance to the chick. The last chick was killed seven-
teen days from the first feeding, when in articulo mortis. In the
lungs of each of those killed at fourteen and seventeen days from
the first feeding, embryo Syngami were found in various stages
of development.

Exp. 10. On July 16th, fed a chick ten earthworms, and re-
peated the feeding for nine successive days. The gapes observed
on the seventh day, as, usual. On July 26th, ten days from the
first feeding, I killed this chick and found a large number of
Syngami in the trachea, and also the embryos in different stages
of growth in the lungs.

Exp. 11. In order to see if Dr. Megnin's theory was correct,
that the eggs would develop within the fowl, I fed a chick about
three weeks old, on July 29th, three perfect Syngami, containing
many thousands of eggs. This chick was carefully watched for
five weeks, and no symptoms of gapes observed. That this re-
sult is correct, we have additional proof in exp. 8, in which large
numbers of perfect eggs were found in the excretions of the
chick, on the fourteenth day after feeding earthworms containing
the embryos of the gape worm. I believe however, if the eggs
should in any manner be retained so as to hatch before they
passed into the proventriculus,* the gapes would be produced,
but think such a case must be very rare, and would be unlikely
to occur unless the embryos were fully developed in the egg be-
fore they were taken by the fowl.

Exp. 12. Three young robins (Turdus migratorius), in the
nest, were fed several infested earthworms each, daily for twelve
days. These earthworms were taken from the same place as
those given the chicks. No well marked symptoms of the gapes
were observed. Two of them were killed, and three or four gape
worms found in the trachea of each. A number were also found
in process of development in the lungs. These birds live almost
entirely on earthworms during a part of the year, and I wished

*The proventriculus is the first or glandular stomach where the gastric juice is secreted,
the gizzard being the muscular stomach where the food is triturated.

12

to know whether they would serve as a host for the parasite, and
thus be instrumental in spreading the disease from farm to farm.
The trachea of robins differs, in its size and anatomical structure,
from that of poultry, especially at its lower part, where the last
ring dilates and forms a second larynx. Syngami generally col-
lect from the lower part of the trachea to its middle, and the
gapes is simply the effort of the bird to obtain more air through
this passage, which is obstructed by these worms. It is evident,
therefore, that birds which have a larger trachea would harbor
a greater number of Syngami without suffering from the gapes.
We see this is the case in chicks after they are several weeks
old, for Syngami can often be seen in their windpipes by open-
ing their mouths and straightening out their necks. Several
worms can thus be seen in large chicks, with very little embar-
rassment to respiration. It is also not improbable that, although
the embryos may penetrate the esophagus, pass to the lungs and
thence to the trachea, the greater part may be coughed up and
swallowed before they are able to obtain a hold on its mucous
membrane. We know from an examination of chicks that very
many of them are thrown off in this way.

Exp. 13. On July 4th, at 5 p. m., fed a chick, about four
weeks old, a large number of Syngami, just hatched, by turning
the water containing them down its throat. On July nth, at 7
p. m., this chick commenced to have the cough or sneeze char-
acteristic of the gapes. July 12th, coughed much more. On
July 13th, at 9 a. m., eight days and sixteen hours after the feed-
ing, I killed this chick and found one single and twenty-nine
pairs of Syngami,

Exp. 14. On August 14th, at 7 p. m., fed a young robin, just
from the nest, a large number of embryo Syngami, hatched in
water, as in the preceding experiment. It was kept in a cage
hanging under a tree, and fed by the old bird. August 22d.
morning: Robin had some symptoms of the gapes, such as rapid
breathing, an occasional gape and shake of the head, and was
inclined to sit on its perch, instead of standing up, as usual.
August 23d: Breathed more rapidly, and evidently quite ill. Au-
gust 26th: Robin continued to grow weaker and breathed more
rapidly, and at times gaped, but the gaping was not as promi-
nent a symptom as in the case of chicks. The robin died the
morning of the 29th, the fifteenth day from the feeding. ( to
examination three fair sized Syngami were found in the trachea.

13

not enough to fill it up, so as to produce much gaping. The
rapid breathing, which was the most prominent symptom, was
readily accounted for by extensive deposits in both lungs, more
especially the right. The lower part of each lung was affected,
and the diseased condition doubtless resulted from the irritation
of the parasites.* Many other feeding experiments with chicks
have been made in different years since the above. 'All of them
thoroughly confirm 'the foregoing ones in every respect, and it
is deemed unnecessary to detail them here. Experiment 13
proves that the embryo of Syngamus does not have to pass
through an intermediate host to obtain any change in structure,
or increase in development, that the earthworm is simply a
bearer, in which it lives in its embryonic condition, and through
which it obtains access to its final host, the fowl. This chick
was kept in the barn and all other sources of the disease excluded,
which was not the case with the robin. The time from the feed-
ing to the production of the disease in the chick was the same
as when earthworms were fed, which is good evidence that it is
the embryo instead of the egg in those which causes the disease.
It may further be stated that in the examination of many infested
earthworms I never yet found one to contain the eggs of Syn-
gamus. In dissecting the robin I found an embryo just emer-
ged from the esophagus into the lung. It was a short distance
above the proventriculus, was sexually developed, being a male,
and thus affords convincing proof that they enter the lung this
way. In a chick I also found a pair of Syngami just united, on
the posterior part of the esophagus, which had the appearance of
having been penetrated by these worms. I have also found the
embryo lying beneath the mucous membrane of the esophagus.

ARTIFICIAL CULTURE.

Exp. 15. On September 23d, 1883, a mature Syngamus filled
with eggs was placed in a small glass dish with a little water, for
the purpose of observing the development of the embryo, the
structure of the young worms and the time required for them to
hatch. We also thought that by comparison in this way they
could be more positively identified in the earthworm. The dish

*This condition resulting from parasites is mentioned by Dr. N. II. Paaren, in the
American Entomologist, Vol. 2, page 149; also, by Dr. George M. Sternberg, from M.
Larrlaine, in an article on the "Production of Tuberculosis by Inoculation," in the
American Journal of Medical Sciences, Vol. LXXXIX, page 18.

14

was kept covered in a warm room (650 to yo° Fahr.), and occa-
sionally placed several hours in the sun. On October 14th, three
weeks from placing them in water, they commenced to hatch.

Exp. 16. June nth, 1885, placed two mature Syngami in a
small glass dish of water, and kept them in a room where they
were not exposed to the direct rays of the sun. On June 28th,
seventeen days from the time they were placed in water, they
commenced to hatch.

As will be seen from the above experiments, the time required
for the eggs to hatch varies under different circumstances. When
they have been mature for several days and kept moist and in a
moderately warm place they will undergo segmentation and the
embryo commence to form. If these eggs are now placed in
water in a warm place it will take but a short time for the em-
bryos to hatch. Again, eggs kept in moderately warm water
will mature their embryos much quicker than those kept cooler.

Exp. 17. December 1st, 1884, placed several embryos found
coiled up in the muscular sac of the segmental organs of the
earthworm, in a small glass dish of water and kept them loosely
covered, in a warm room. These embryos were thought in the
beginning of the investigation to be those of SyHganuis, and this
method was adopted to see if any growth or development of
structure would take place in water, whereby we might decide
the question. In from five to seven days they grew to many
times their original length, and were developed into male and
female. A small number of eggs were also seen in different
stages, within the oviducts and scattered about the bottom of
the vessel. These worms correspond with the description and
figures in the Micrographic Dictionary under the head of Augtiil-
lulidiac, and are thus excluded from being the embryos of Syn-
gamus.

Exp. 18. Several embryos taken from the intestinal canal of
the earthworm, where they were found surrounded by mucus,
were placed in a glass dish of water and kept, as in the fore-
going experiment, seven days. These embryos, after a few
hours, coiled themselves up at the bottom of the dish, and for
the most part of the time remained in this condition, occasionally
uncoiling and moving about a short distance. No growth or
development of structure took place. These embryos correspond
in size and structure with those hatched from the eggs of Syn-

i5

gamus, and later in the investigation were fully identified as being
the same.

Exp. 19. Placed several embryos from the intestinal canal of
the earthworm, like those in the preceding- experiment, in a cov-
ered glass dish of water, and then in an incubator, and kept them
at 1050 Fahrenheit for seven days, at which time they were alive,
but no change of structure or development had taken place.

Exp. 20. One pint of blood from a calf was allowed to stand
in a glass fruit jar until the solid portion had settled, leaving the
serum at the top. On May 5th, at 9 a. m., one dram of this
serum was placed in a Syracuse solid watch glass, with ground
edges, containing twenty of the last described embryos. These
embryos had been kept in the watch glass in water one week,
and were nearly all lying quietly coiled up about its center. The
most of the water was removed by a pipette before the serum
was added. As soon as this was done the embryos uncoiled
and became quite lively, as though they had at last found their
natural element. The watch glass was placed in an incubator,
covered by another one with ground edges, but leaving a small
space for air. The temperature had previously been regulated
so as to remain at 1050 Fahr. At 9 p. m., on examining them
with the microscope, they had slightly increased in size and were
commencing to moult. On May 6th, at 9 a. m., they were again
taken from the incubator and examined, when the process of
moulting had still further advanced. At 4 p. m. I found them
all dead. The culture fluid had become putrid.

Exp. 21. May 7th, 4 p. m., completely satisfied that I was
on the right track, I removed four more embryos from an earth-
worm and placed them in another portion of serum, and in the
incubator as before. On May 8th, at 9 a. m., removed them to
another watch glass containing fresh serum, by taking them up
under an inch objective with a small splinter of wood whittled
to a fine point. At 9 p. m. the same day they were again removed
to fresh serum. One was found dead, another had moulted, and
the two others had nearly completed that process. May 9th, 9
a. m., they were seen to have increased in size, and were removed
to another portion of serum. These embryos lived between four
and five days in the incubator, and were about moulting the second
time. They were sufficiently developed to show the peculiar
structure of the mouth of Syngamus trachealis. One of them

i6

measured .0139 inch in length, and the exuvia, in which it still
remained, .0227 of an inch. (See figure 3.)

Exp. 22. Four of the embryos from the earthworm were
placed in one dram of egg albumen, after it was beaten to render
it fluid. They were placed in the incubator as before, and
changed to fresh albumen daily. After being kept in this wav
six and one-half days, they were alive, but there was no change
in their structure or size, or any appearance of moulting percept-
ible. Evidently the proper food for their metamorphosis and
growth was not contained in this fluid. In these culture exper-
iments the incubator used was one in which the heat could not
be thoroughly controlled. It is believed with a good one and
more experience better results could be attained. It is also
thought the blood serum of a fowl would be best adapted for
this purpose. This method of artificial culture of animal parasites
is believed to be new, and if varied according to the different
circumstances in which they are found in nature will, we think,
render easy the solution of some of the most difficult questions
as to the life history and embryonic forms of many of these
creatures. The subject is of great importance, for large num-
bers of both human beings and animals perish each year through
their agency. Moreover, it is not far removed from that great
question which occupies so prominent a position before the
medical profession at the present time. I refer to the germ the-
ory of disease. The one is an animal, the other a vegetable par-
asite. The method of artificial culture is now being used for
working out the latter; I see no reason why it cannot be success-
ful in the former.

EMBRYOLOGY AND DEVELOPMENT OE SYNGAMUS.

The egg is formed out of the granular material seen near the
extremity of the ovarian tubes. It is shaped into small round
bodies which pass down towards the uterus, within the horns of
which they are supposed to become impregnated, and receive the
hard external coat called the shell. Within the body of the female
Syngamus, about fourteen days after its entrance into the fowl,
are found several thousand eggs in various stages of develop-
ment, from the granular material of which they are formed, as
it exists in the ovaries and ovarian tubes, to the perfed egg in
the uterus. The perfect egg is oval, about .004 inch in its long,

17

and .0025 inch in its short diameter. At each end is a valve or
lid which drops off when the embryo emerges from the egg. It
has been the general opinion among naturalists that the mature
eggs of Syngamus were never discharged through their natural
outlet during the life of the female, that being rendered impos-
sible by the intimate union of the genital organs of the sexes,
whereby the outlet of the vagina was completely closed. They
believed that only at the death of the worm and disintegration
of its body were the eggs set free. That such is not the case
in some instances, / knoiv, for I have distinctly seen, under the
microscope, with a power of fifty diameters, the eggs pass out at
the posterior part of this union in a living pair, just removed
from the trachea of a chick. Two or three eggs were discharged
at regular intervals, each minute. On close observation there
was clearly observed movements of the worm, showing the nat-
ural expulsive efforts, followed by the extrusion of the eggs.
Now, in about fourteen days after the feeding of earthworms1 con-
taining the embryos of Syngamus, we have, in several later exper-
iments, some of which are not herein recorded, observed the per-
fect eggs of Syngamus in the excretions of the chicks. These
chicks were then killed and the living pairs of Syngami found
attached to the mucous membrane of the trachea. Some of
these pairs had not yet attained their complete growth, yet the
eggs, near the genital outlet, were fully developed. None of
them were found dead and their bodies breaking up in the
trachea. From these observations we have no doubt that the
living worm, contrary to the opinion heretofore entertained, does,
during its life, extrude a large number of perfect eggs, but al-
ways dies while many yet remain in its body, which are set free
when that decomposes. I have never been able to press the eggs
out through the vagina in a dead Syngamus. This may be one
reason why naturalists have thought they did not pass out when
living that way, but I believe all dead animals have their genital
passages contracted in the same manner. It has also been the
general opinion that the eggs furthest advanced in a mature
Syngamus while living and just removed from the trachea of a
fowl contain the perfect embryo already moving actively about
within the shell. That such is not the case we believe and will
briefly give our reasons for this opinion. In experiment No. 8,
it will be seen that a chick fed earthworms containing the em-
bryos of Syngamus developed the gapes, and in fourteen days

i8

from the time of the first feeding great numbers of the eggs of
Syngamus were found after they had passed through the fowl's
intestines. These eggs passed from perfect worms, which were
found attached to the trachea of the chick, killed the same day.
Now, the eggs which passed through the chick, and those found
about the perfect worms in the trachea, showed no sign of em-
bryonic formation. Moreover, we will say that after the exam-
ination of many perfect worms removed from the trachea, we
have never found the embryo developed within a single egg at
that time. In our experience, it takes these eggs not far from
three weeks, varying somewhat with the temperature, to mature
and bring forth their embryos. We believe Syngami, in which
active embryos wer» found within the egg, had been for many
days mature, and probably kept in a moist condition, either
within the body of the bird or external to the same. The em-
bryo of the lung worm of calves (Strongylus micrurus), is fully
developed in the egg while in the lungs of the calf. Possibly,
reasoning by analogy has had something to do with this opinion
heretofore entertained concerning Syngamus. It is evident the
eggs, scattered over the ground in the natural way, hatch much
quicker during the hot months of summer than later in the sea-
son. Indeed, it is quite probable that most of these last perish
on account of the cold, without the formation of an embryo.

DEVELOPMENT OF THE EMBRYO.

The process of development from the egg is as follows:
The yolk undergoes segmentation; that is, becomes divided into
2, 4, 8, etc., round masses or spheres, this division being con-
tinued until it assumes the mulberry state. The embryo is devel-
oped from this around the inner part of the shell, in the form
of a circle. Before it emerges the embryo usually coils itself
within the egg, like the figure 8, from which it generally comes
out head first. The time required for the perfect egg to pass
through the different stages, until the embryo issues from it
varies, as heretofore stated. On one occasion a few of the em-
bryos came forth in seventeen days. The embryo on emerging
resembles an Anguillula, but its movements are not as rapid as
most of the worms belonging to this order. It is about .01 1 inch
in length, and .0005 inch in width at its middle. The posterior
half of the body is filled with a fine granular matter. After the

19

embryos have been in water a few days they moult, losing about
.0005 inch in length; their tails are then more blunt. Sometimes
they pass through the first moult while coming out of the egg,
leaving the old skin within.

THE EMBRYO IN THE EARTHWORM.

After many careful microscopic examinations of the embryo,
as found in the earthworm, I have arrived at the conclusion that
it does not differ in its structure, so far as can be discovered, from
the embryo which hfis passed through one moult, after the egg
has hatched in water. The method of finding them in the earth-
worm is as follows: Select a poultry yard where chicks have had
the gapes for several years, so that the earthworms may have
plenty of the parasites. From near the surface of bare spots of
ground, which chicks with the gapes have frequented, take some
of the earthworms and examine them with the microscope. The
following method is recommended: Throw, the earthworm to be
examined into a solution of common salt (chloride of sodium),
having the strength of about two ounces to the pint of water.
When it ceases to move, rinse in pure water; then, with sharp-
pointed scissors, slit the worm its entire length. Spread out on
each side, to expose the alimentary canal. In order to intelli-
gently proceed, we will briefly describe the organs contained
therein. They consist of the mouth, pharynx, esophagus, crop,
gizzard and intestine. Directly connected with the esophagus,
about its middle and posterior part, are found six white bodies,
three on each side called the esophageal or calciferous glands.
The esophagus passes directly into the crop, which is just in front
of the gizzard. Following this is the intestine, which passes
through the remaining portion of the worm. We cut off the in-
testine, just back of the gizzard, and taking small pieces, about
one-eighth inch long, place them on a watch glass with a little
water, pick them well in pieces, and examine carefully with an
inch objective. We generally find the embryos a short distance
below the gizzard, not often more than half way to the tail. There
are numerous kinds of parasites which inhabit the earthworm,
some of them numbering thousands in a single worm. We have
also found the earthworms in different localities to harbor very
different kinds of parasites. The method of distinguishing the
embryo of Syngamus is its size, description as here given, and

20

general appearance as seen in the engravings. We believe it is
taken in by the earthworm with its food, and passes down into
the intestine, where it remains until transferred within its host to
the digestive organs of some bird, or after a time passes through
into the soil and perishes. This method of taking in the embryo
by the earthworm is the common law in nature, through which all
creatures, man included, obtain their intestinal parasites.

THE EMBRYO OF SYNGAMUS IN THE FOWL.

The embryo passes into the crop within the intestine of the
earthworm. We wish to determine at what point it leaves the
digestive canal and passes into the lungs and trachea of the chick.
We have never been able to trace the embryo below the esopha-
gus, after many examinations of chicks dead of the gapes. If we
admit that they do not pass through the proventriculus and giz-
zard alive, which I have no doubt is the truth, there are only two
organs, the crop and esophagus, through which they could gain
admission to the lungs. The crop is simply a dilatation of the
esophageal structures, and acts as a reservoir for the food. We
believe the embryo passes through the esophagus just above the
proventriculus, for the following reasons: The distance to the
lung structures is very short, only the thin wall of the esophagus
intervening. The orifices of the lenticular glands of the esopha-
gus are of greater diameter than the embryo, so it could readily
enter through them. That it does so we believe, for we have
found them beneath its mucous membrane. The pulmonary
bronchi ramify over the outer surface of the esophagus, through
the substance of which there are numerous tubular structures,
which, it is not improbable, may be connected with them. We
have seen the embryo just emerged from the esophagus into the
lung, and have in all the chicks carefully examined for that pur-
pose, after dying of the gapes, found several echymosed spots,
which looked as though the embryos had passed through. We
have also found them recently united on the outer wall of the
esophagus, one pair being the smallest we ever saw. In dissecting
chickens dying of the gapes, we have, many times, Found the
esophagus adhering to the lungs, as we believe from the inflam-
mation caused by the passage of the embryos. This condition of
echymosis, and adhesion of the esophagus to the lungs, we have
never found in any chicks we have dissected which did not have

21

the gapes. Both male and female embryos do not develop beyond
a certain point until union takes place. After this they pass up
into the trachea, where they attach themselves to the mucous
membrane and attain maturity.

ANATOMICAL DESCRIPTION.

We shall not attempt any extended anatomical description of
Syugamits trachcalis. The illustrations accompanying this investi-
gation will show its appearance in the different stages of its ex-
istence. We will briefly say that the mouth in this Genus is large,
circular, and surrounded by four outer membranous and six inner
chitinous lips. The young worm has eight inner lips, two of
which uniting with two others, reduces the number to six in the
adult worm. Within it is hollowed out, and contains around the
opening to the digestive apparatus, eight lance-like organs, which
are supposed to pierce the mucous membrane for extracting the
blood of its host.

THE MALE.

The male has been found coupled on the external wall of the
esophagus of the chick when .035 inch long, and .002 inch wide.
At maturity it attains the length of about .24 inch, and a breadth
of about .02 inch. The diameter of the head exceeds that of the
body, which is round, and its posterior part, containing the genital
organs and anus, is united to the anterior part of the vulva of the
female by a membranous hood-like organ, called the caudal
pouch. This organ is elongated in front, with about one-third
of its diameter cut out on its posterior part, where it is free from
the female. It is supported by eight principal ribs, which are sub-
divided as follows: The posterior ribs on either side are double;
next to these on each side they are trifid, followed by a single rib,
between which are the two anterior ribs, also trifid. These divi-
sions of the ribs, eighteen in number, each have at their extremity,
which reaches to the circumference of the caudal pouch, a disk
or sucker, by means of which the male attaches itself to the genital
organs of the female and maintains so strong a hold, that even
after death they are separated with much difficulty. There is no
actual growing together of the organs, as has been the commonly
received opinion, for they can be separated entire by careful
manipulation in diluted glycerine. Within is seen the digestive
and internal genital organs.

22

THE FEMALE.

The female has been found united with the male on the
esophagus when .055 inch long and .0025 inch in width, and in its
adult state sometimes measures .875 inch in length, by nearly
.045 in width. It is of a bright red color from the absorption of
the hematin of the blood upon which it lives. When mature it is
irregularly cylindrical, curved, and often variegated by the white
winding uterine horns filled with eggs. The tail is conical and
just in front of its extremity is the anus. The vulva is a short
distance back of the head and is attached at its anterior part to
the caudal extremity of the male. At its posterior part this union
is incomplete, the perfect eggs passing out here through the
vagina. The digestive and genital organs can be traced within.

PREVENTION OF THE GAPES.

The very best results which can be attained from the study of
disease is its prevention. If the only way in nature by which fowls
contract the gapes is from eating earthworms containing the
embryos of Syngamus, it follows if none of these were eaten the
disease would become extinct. We believe, after many years'
study of the gapes, that this is the only natural way in which
fowls contract the disease, but, should they take in the embryos
in any other way the disease would be equally liable to occur. We
have never observed this to take place, and believe it never docs
except through the instrumentality of man. Adopting this view,
there are two methods of prevention, either one of which will
prove effectual. First, keep young fowls from the ground where
earthworms are infested by the embryos. Second, destroy the earth-
worms containing them, when the fowls could be allowed their
liberty. We had thought a third method rmght be added, namely,
to mix with the bird's food some anthelmintic, which, if worms
containing the embryos were eaten, would destroy them without
injuring the fowl. This opinion was changed after the experi-
ments detailed belowwere concluded. The first method consists in
either keeping them on wooden floors, or some grassy plot or
ground where the disease has never existed. The second method,
that of destroying the earthworm, involves the question as to
what is the best method of doing this. The article to be chosen
must be cheap, effective, readily applied, and safe to use. We
have experimented with three different substances, each of which

23

possesses to a considerable degree these qualities. They are
common salt (chloride of sodium), lime (oxide of calcium), and
wood ashes (mostly composed of potassa and its carbonate). In
the experiments medium-sized earthworms were used, and the
embryos of Syngamits were taken from the intestine of the earth-
worm.

EXPERIMENTS WITH EARTHWORMS AND EMBRYOS

OF SYNGAMUS.

Exp. i. An earthworm just dug, and with the dirt still adher-
ing to it, was thrown into dry lime which had been slacked for
several weeks. At the end of twelve minutes it was dead.

Exp. 2. Another earthworm was thrown into linie water; in
seven minutes it ceased to move.

Exp. 3. An embryo of Syngamits trachealis was placed in lime
water; it was observed for two hours, at the end of which time it
was still alive and active.

Exp. 4. An earthworm was placed in a solution of common
salt having the strength of one-fourth pound to the gallon of
water. In six minutes it was dead.

Exp. 5. An embryo of Syngamus placed in the above solu-
tion lived thirty-three minutes.

Exp. 6. An earthworm placed in a solution of salt having the
strength of one-half pound to the gallon of water lived four
minutes.

Exp. 7. An embryo of Syngamus placed in the above solu-
tion ceased to move in fourteen and one-half minutes.

Exp. 8. An earthworm placed in a salt solution having the
strength of one pound to one gallon of water lived about three
minutes.

Exp. 9. An Embryo of Syngamus placed in the above solu-
tion lived three minutes.

Exp. 10. An earthworm thrown on dry salt ceased to move
in somewhat less than three minutes.

Exp. 11. An earthworm thrown on dry ashes lived a"bout
twelve minutes.

Exp. 12. An earthworm placed in lye made by pouring warm
water on wood ashes and letting it stand one hour, the proportion
being one-half pound of ashes to one gallon of water. The earth-
worm ceased to move in three minutes.

24

Exp. 13. An embryo of Syngamiis placed in the above solu-
tion was apparently unaffected at the end of twelve hours.

Exp. 14. An embryo of Syngamiis placed in a watch glass
containing a mixture of water and asafoetida, many small pieces
of the latter being scattered over the bottom. At the end of one
hour it was unaffected, although almost constantly in contact
with the lumps of asafoetida.

Exp. 15. An embryo of Syngamiis placed in a watch glass
with water, and several small pieces of an onion, making a strong
solution, were added to the same. At the end of six hours very
little abatement in the vigor of its movements was perceptible.
In twelve hours it still lived, but its movements were very slow.

The result of the above experiments may be stated as follows:
Lime, salt, and ashes are all effective in destroying the earthworm.
Lime water and lye of the strength used seemed to have very
little effect on the embryo of Syngamiis. Doubtless, a stronger
solution of ashes would kill it, and it is probable that lime in
substance would also be effective. Salt not only destroys the
earthworm, but it also kills the embryo of Syngamiis. The anthel-
mintic power of asafoetida and the onion has disappointed us
much. The latter belongs to the same family (Allium), and has
similar properties to garlic, which has been so highly recom-
mended as a specific in the gapes. Ashes, lime or salt may then
be used. The first two can be spread over the ground. Lime, in
the form of lime water, is exceedingly cheap, but, exposed to the
air, or in the soil soon combines with carbonic acid, forming car-
bonate of lime, which is probably harmless to the earthworm. We
believe salt is more reliable, and it has also the additional ad-
vantage of destroying the embryo of the gape worm in the soil.
It can be used in poultry yards in the proportion of one pound to
the gallon of water, or, if the soil is very moist, two pounds would
be better. If a large extent of ground is to be treated, the salt
could be scattered in substance over the surface and left to be
dissolved by rain or plowed under, taking care that none of it
is eaten by fowls. This method has been adopted by setae with
success, no more gapes having developed in their chicks. All
poultry dying of the gapes should be burned, and not left upon
the ground, or even buried deep, as advised by some, for the eggs
may hatch, and the embryos be taken by the earthworm to the
surface to propagate the disease.

25

CONCLUDING REMARKS.

Before closing-, we wish carefully to examine a few points
concerning the life history of Syngamus trachealis, and the propa-
gation of the gapes. First, do fowls contract the disease by pick-
ing up the eggs, or mature Syn garni containing them? Dr.
Megnin's parrot was claimed to have taken the disease from eat-
ing, on August 7th, four mature Syngami filled with eggs. The
first symptoms of the gapes manifested themselves on August
28th, twenty-one days after the feeding, and the bird died Sep-
tember 10th, on the thirteenth day of the disease. We believe if
the eggs were retained and hatched before they reached the
proventriculus, the gapes would result. But we think such a case
is exceptional, and not the way in which the disease generally
occurs. In proof of this we will not only bring forward the chick
fed mature Syiigami (see feeding exp. 11), but also, the general
fact that chicks, about fourteen days after they take in the
embryos of Syngamus, have large quantities of mature eggs pass
through their intestines into the soil. According to first theory,
these eggs should hatch within the chick; it would thus become
self-infecting, and would almost necessarily die. On the con-
trary, after chicks are a few weeks old they generally recover,
their windpipes being large so that the usual number does not
very materially interfere with their respiration. That the eggs are
not contained in the earthworm and thus taken we believe is true,
for, in the examination of very many infested earthworms during
the past fourteen years, we have never found an egg of Syngamus.
It is also evident that the time required to produce the gapes by
feeding earthworms is too short for the eggs to hatch and the
embryos to pass through their different stages. Again, the eggs
are so small they could not be seen, as they were scattered over
the ground, and picked up by chicks, and it is highly improbable
that they would retain their vitality through the long winter
months in this climate, and propagate the disease in chicks the
following summer. We are aware that the eggs of various in-
sects survive the winter, and continue their species from year to
year, but we have found by experiment that the eggs of Syngamus
trachealis will not hatch after being kept a few weeks, fatty de-
generation takes place, and their vitality is destroyed. We con-
sider it unnecessary to bring forward further proof on this point.
Dr. Megnin himself abandons the theory, and says: "The birds
are infected by drinking water containing the embryos." We are

26

then forced to the conclusion that the living- embryo, in some
manner, finds its way into birds, and is there developed into the
perfect worm. That the gapes can be artificially produced by
feeding the embryos of Syngamus hatched in water to chicks, we
readily admit, for we have proved such is the case by experiment
13. But we deny that this is the natural way in which they con-
tract the disease. In this climate of ours, with a long severe
winter, the thermometer is often down to zero, water, when re-
maining on the surface of the ground would be frozen a hundred
times, and during the warm season none would be found except
in rainy weather. How then, we ask, would it be possible for
the embryo to live through the cold season in water, and be taken
by chicks the next spring, in the water they drink from the sur-
face of the ground. Some of the Nematoid worms, to which class
Syngamus belongs, can be brought to maturity by being taken in
water. Nevertheless they have intermediate hosts which act as a
bearer, exactly as the earthworm acts as a bearer to the gape worm.
They differ from most of the tape worms which have to pass
through an intermediate host, in which they are partially devel-
oped, to prepare them for a final development in their last host.
To illustrate: Trichinae belong to the Nematoid worms, the
same class as the gape worm, and could be propngated in man by
drinking them in water, but did you ever hear of this taking place
in nature? No! They get them from their intermediate host, the
hog. The question is not what might happen, but what does
actually occur in nature, without the intervention of man. I do
not believe the Creator, in his infinite wisdom, has designed that
the gape worm should be without a bearer, for you can easily
perceive what would become of the poor worm in these Northern
States were such the case. The soil is often frozen to a great
depth, and it would be utterly destroyed. Besides this, it could
not be picked up by a chick or bird, except by the merest acci-
dent, for it is so small it could not be seen. No! this is not so.
It has been wisely decreed that the earthworm should be its inter-
mediate host, in the intestine of which it finds all the nourishment
necessary to sustain it. When winter comes it is carried deep into
the ground, out of all reach of cold, and in the spring is brought
again to the surface ready to be picked up in the earthworm, and
pass through the remaining portion of its existence in its final
host, the fowl. Now, the proof is positive, and must be acknowledged,
that earthworms do contain the embryos of Syngamus trachealis, and

27

that the gapes can be produced by feeding the earthworms containing
them to chicks (see the various experiments herein detailed). But,
some say it is only an accidental host of the earthworm, taken
in with the particles of earth, leaves, etc., while boring through
the soil, and that the embryos may even be used as food by the
earthworm. I have not the slightest faith in its being an acci-
dental host of the earthworm, temporarily taken in with leaves,
grass, etc., or used as food. If this was the case, why should we
find it, as I have often done, in many earthworms in an infested
locality, in midwinter, down deep in the ground, in the same posi-
tion as in summer, in the intestine of the earthworm? Why did
it not pass off with leaves and other matter used as food, instead
of remaining throughout the year? I have found twenty in a
single earthworm, and often five to ten. If the embryo was taken
in as an accidental host, I see no reason why we should not at
times find some of the eggs of Syngamus in the earthworm, but as
before stated, we have never found one. In all our study of the life
history of the gape worm,we have never found any way in nature ^with-
out the intervention of man, through which they obtained access to birds,
except the earthworm. There is no food more natural for fowls
than these. Chicks, two days old, eat them greedily. No embryos
of Syngamus have ever been discovered, on repeated examinations,
in any other forms of animal life about the coops of chicks having the
gapes, except earthworms. These examinations were made with
the microscope, and also by feeding experiments with chicks. No
embryos like those of Syngamus, were found in earthworms which
did not produce the gapes by feeding them to chicks. / have made
inquiries in various parts of our country, where no earthworms are
found, as to the existence of gapes, and have invariably received the
reply that their fozvls do not have the disease. The robin and other
worm-eating birds which act as hosts for Syngamus, without
question disseminate the disease from one farm or part of the
country to another. When you remove your chicks to new
ground where there has never been any gapes, the earthworms
will not contain the embryos, and your chicks will be free from
the disease. This has been demonstrated many times in this
vicinity. Also, the fact that using a strong solution of salt on the
ground, and thus killing the infested earthworms about coops
where chicks have previously had the disease, would entirely pre-
vent any outbreak the following year. It is a matter of common
observation, that the gapes is more prevalent during wet seasons,

28

than dry ones. This is easily explained; the reason being that
earthworms are more plenty on the surface of the ground, where
they are easily picked up by chicks. It is also well known that
when chicks are let out in the early morning, they are more apt
to have the gapes. This was thought by many to result from their
getting wet and cold, but it is easily explained by their finding the
earthworms out at that time, when if they were not let out until
the moisture was dried off the ground, the earthworms could not
be found, they had retired into their burrows. The old adage,
"The early bird catches the worm," well illustrates this point. It
is also a well-known fact that chicks kept near a chip yard, were
apt to have the gapes. This is readily explained by reason of
their easily getting earthworms by scratching the chips from the
surface of the ground, earthworms being found plenty in such
places.

FINALLY, THERE IS NOTHING CONNECTED WITH
THE GAPES WHICH CANNOT BE FULLY, AND CLEAR-
LY EXPLAINED THROUGH THE AGENCY OF EARTH-
WORMS.

We will recapitulate the several points we consider established
by this investigation. First, that the earthworm is the inter-
mediate host of Syngamus trachcalis, is proved by many successful
experiments in feeding them to chicks. None of the chicks fed
earthworms from an infected spot, failed to have the gapes in
seven days. On microscopic examination, the embryos of
Syngamus were found in these earthworms. That no other forms
of animal life about the coops act as a host for Syngamus, proved
by feeding all those found to chicks and they failed to produce
the gapes; also, none of the embryos were found in them on ex-
amination with the microscope. That all earthworms do not con-
tain the embryos of Syngamus, proved by feeding three chicks
earthworms from a place where no gapes existed. They failed to
have the gapes, rind no embryos of Syngamus could be found in
the earthworms with the microscope. That the earthworm is
only a bearer, or means of conveying the embryo to the fowl, is
proved by feeding" the embryos hatched from the eggs to a chick,
and thus producing the gapes. Also, the fact that the embryos
in the earthworm do not develop, either in growth or structure,
more than when they emerged from the tgg. That the embryo
of Syngamus is not an accidental host of the earthworm, proved
by finding them in considerable numbers, in main earthworms,

29

in an infected spot, throughout the year. No earthworms, no
gapes. This view is supported by inquiries made in various parts
of the country where there are no earthworms, in which places,
they say the fowls do not have the gapes. The embryo of
Syngamus has been found in the earthworm, and identified by
tracing it through its different stages from the earthworm to the
trachea of the chick, and also by artificial culture. That they pass
through the esophagus of the chick is demonstrated by finding
them beneath its mucous membrane, and just after they had
passed through into the lungs; also, by finding the esophagus
adherent to the lungs in many chicks which had the gapes, this
condition not being found in those which did not have this disease.
That the disease is transmitted from one year to another by drink-
ing water containing the embryos, is rendered impossible in a cold
climate, where the water is frozen many times during the winter,
and often dried from the surface in the summer. That the robin
(Turdus migratorius), and probably many other worm-eating
birds may act as a host for Syngamus, and thus be instrumental
in spreading the disease, is proved by feeding three robins and
finding full-grown worms in their tracheas. That the union be-
tween the genital organs of the male and female is incomplete at
its posterior part, so that the eggs can be, and are readily ex-
pelled during the life of the worm, proved, by seeing this take
place under the microscope. That the mature Syngamus, while
yet in the trachea of the fowl, lays its eggs, which are coughed up,
swallowed, and pass through the intestines of the fowl to the
ground. Proved, by finding the eggs in the excretions, and the
living worms from which eggs were passing, in the trachea. That
the genital organs of the sexes are not grown together, proved,
by separating them without rupture, and finding them to adhere
by means of suckers on the genital organs of the male. That the
mature egg does not contain an embryo is proved by examining
them after they are naturally expelled by Syngamus, and finding
that two or three weeks are required for the embryo to develop in
them. That the embryo of Syngamus is but slightly affected by
the anthelmintics which have been used to prevent and cure the
disease, as asafoetida and garlic. They cannot be relied on for
this purpose. Lastly, to prevent your fowls from having the
gapes, remove them to some spot where the disease has never
existed, or destroy the infested earthworms in the ground with
common salt.

30

The life history of Syngamus trachealis is as follows: Earth-
worms containing the embryos are eaten by the fowl. The
embryos are liberated from the intestine of the earthworm and
work their way through the esophagus into the lungs and bronchi.
Here they pass through the nymph stage and acquire sexual
maturity. The male and female then unite, work their way into
the trachea, and attach themselves to its mucous membrane by
their sucker-like mouths. Between six and seven days are re-
quired from its entrance into the fowl until its attachment to the
trachea. In about seven days more the eggs within the body of
the worm become mature. They are coughed up into the mouth,
swallowed by the fowl, and pass through it into the soil. In about
three weeks, the time varying somewhat according to the tem-
perature, these eggs, exposed to the moisture and sun, hatch ; the
embryos are taken in their food by the earthworm, where they
remain until picked up by some bird, when the above process is
repeated. Some years one-half or two-thirds of the young fowls
in certain localities are destroyed by this disease. This investiga-
tion proves that if they were kept from eating infested earth-
worms, that terrible scourge of poultry, the gapes, would be en-
tirely prevented. Not only this, but it serves as a key to unlock
the mysteries surrounding several other diseases, caused by para-
sites belonging to this family; namely, the lung worm of calves
(Strongylus micrariis), the lung worm of hogs (Strongylus cb'iga-
tus), the lung worm of sheep (Strongylus filiaria), the grouse
disease (Strongylus pcrgracilis). Great numbers of calves, hogs,
sheep and grouse are yearly destroyed by these parasites. Their
intermediate hosts have never been discovered. From certain
inquiries which I have made, I venture to predict that the earth-
worm will be found to be their intermediate host.*

*Cobbold in hi? work on " Parasites," page 336-346, after a series of observations states
his belief that the earthworm may act as an intermediate host for Strongylus micrurw.

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