Studies on growth, development, and infectivity of Philophthalmus hegeneri Penner and Fried 1963 in the chick.

A reinvestigation of the growth curve of Philophthalmus hegeneri in chicks showed rapid growth for the first 17 days after infection. After this, the growth rate declined for multiple infections (two or more worms per eye), and after 20 days, adults in monometacercarial infections ceased appreciable growth and never attained reproductive maturity. These results are similar to those reported by Fried (1962), but here adults were approximately 0.5 mm shorter in all cases and were slower in producing mature eggs. When worms from 28 to 36 days old from monometacercarial infections were transplanted into multiple infections, normal growth occurred. Worms recovered from multiple infections and transplanted singly grew normally for at least 18 days but recovery rates were extremely low. When P. hegeneri adults over 20 days old from monometacercarial infections were transplanted singly with Philophthalmus megalurus adults, growth was not stimulated in either species.