Observations on the biology of the poultry cestode Davainea proglottina in the intestine of the host.

In the course of some experiments dealing with the anthelmintic treatment of tapeworm-infected birds, it became necessary to estimate the degree of infection in the living birds. The data presented in this paper were obtained in the course of those studies. White Leghorn chickens were experimentally infected with Davainea proglottina by feeding them garden slugs (Agriolimax agrestis) containing mature cysticercoids. The slugs had been fed gravid segments of the tapeworm three to four weeks previously. Infection in the birds was proven by the finding of gravid segments in their feces. The feces were collected by placing the birds in separate screen-bottomed cages which rested over pans containing enough 1? per cent formalin solution to cover all the droppings passed in 24 hours. At the end of that time all the material was collected and allowed to settle in tall jars. The supernatant fluid was discarded and the sediment examined in small portions with a wide-field microscope until all of the segments had been counted. A simple technique was used for counting the tapeworms in the intestine. The bird is first starved for 18 hours. Then 60 cc of 5 per cent formalin solution at 45? C. is injected directly into the gizzard by means of a long, fairly pliable, hard rubber cannula and a rubber bulb. If the solution is injected slowly, all of it will go into the intestine. After about ten minutes the bird is destroyed and the intestine removed. Care is taken not to lose any of the contained fluid since many of the tapeworms will free themselves from the mucosa during this treatment. Twoinch lengths of intestine are slit open in a petri dish into which is poured enough water to cover the mucosa. The majority of the worms are fixed in situ and may be distinguished quite readily since the opaque, white segments stand out against the reddened villi. The worms, including the scoleces, are picked out of the mucosa quite easily with a pair of needles under a wide-field binocular microscope. After removing all of the worms that can be seen, a further check on very small ones is made by scraping the mucosa and examining the scrapings in a small amount of water.