Studies on the Life History of the Chicken Tapeworm, Raillietina (Paroniella) kashiwarensis Sawada

(1) The morphology, the habitat and the life history of Raillietina (Paroniella) kashiwarensis are described. (2) The uterus is divided into capsules, each containing a single egg. The egg is oval in shape, 64 to 88 μ by 44 to 72 μ. The onchosphere is spherical in shape, 20 to 28 μ by 16 to 24 μ, being enveloped by three sheets of thin membranes and situated in the center of theegg. (3) The observations on the motility of the senile proglottides show that ; (a) the senile proglottides just after voiding in the feces continue to move some time ; (b) they migrate outside the feces mass in which they are evacuated. (4) The onchosphere can not develop into the mature cysticercoid in the adult workerant of Euponera solitaria. But as soon as the onchosphere enters into the young ant-larva, it begins to grow and develops into the mature cysticercoid in about 30 days, during which the young ant-larva of Euponera solitaria grows into adult worker-ant. (5) The cysticercoid is approximately ovoid, 296 to 637 μ in length, 237 to 416 μ in width. The conspicuous invaginated groove of the larval scolex which entered into the central cavity of the bladder is observed at the anterior end, but any caudal appendage is not observed at the posterior end. (6) The cysticercoid in stages infective to chickens is parasitized in the abdominal cavity of the adult worker-ant of Euponera solitaria throughout the year. But the infection rate reachs the highest peak in November just before the ants burrowed into the ground for their hibernation. (7) The older a chicken yard is, and the younger the chicken living there is, the higher the infection rate of the cysticercoids in the ants collected there is. (8) The longevity of the mature cysticercoid in the abdominal cavity of the ant can not be clearly determined. But the cysticercoid may survive in it for 4 or 5 months at least. (9) When the cysticercoid enters into the small intestine of a chicken and clings to its wall by means of many hooks, it begings to grow immediately. The graphic presentation (Fig. 26) of the data of the growth within the host (Table 7) suggests that during about the first 5 days after the initial infection, its growth is very slow, but from the 5th day to the 13th day when the separation of the senile proglottides begins, the growth is rapid. This fact may be expressed in the following formulae : L(length)=(2.5)e0.38n, W(weight)=(0.018)e0.72n, W/L(weight/length ratio)=(0.007)e0.35n, where e is the natural logarithm base and n is the age in days.(10) As Table 7 indicates, the weight/length value reaches one peak on the 13th day after the initial infection. This peak means the beginning of the separation of the senile proglottides, but the subsequent increases in the weight/length value have nothing to do with separation of the senile proglottides. (11) The production of the proglottides begins on the 4th day after the initial infection. The increasing ratio of the number of proglottid is the highest on the 4th day and gradually falls from the 6th to the 13th day. Then it remains almost unchanged, and large increase and decrease of the number of proglottid are not seen from the 15th day to the 23rd day. (12) Larval tapeworms engage in their struggle for growth in the small intestine of a chicken till about the 4th day after the initial infection, so some variations are observed in the linear growth and the number of proglottid, but as the tapeworms reach maturity, the variations are observed no more. (13) The testis is first found on the 5th day after the initial infection, the ovary and the vitelline gland on the 7th day, the gravid proglottid on the 9th day, and then, the senile proglottid on the llth day. And on the 13th day, separation of the senile proglottid is observed in most of the tapewoms. (14) The longevity of the adult tapeworm in the small intestine of a chicken can not be clearly determined. But the tapeworm may survive in it for 4 or 5 months at least. (15) Only Euponera solitaria among the 13 species of the small insects and earthworms which collected in the chicken yards at Nara Agricultural Experiment Station and Nishio poultry-farm harbored mature cysticercoids of Raillietina (Paroniella) kashiwarensis. Gallus gallus domesticus is infected with the tapeworms by swallowng Euponera solitaria harboring full-grown cysticercoids. Accordingly, Euponera solitaria is one of the powerful intermediate hosts of Raillietina (Paroniella) kashiwarensis