On the Cytology and Life History of the Amoebae with Descriptions of Two New Species

Abstract

It was shown by Graybill and Smith (1920) and Smith and Graybill (1920) that blackhead in turkeys and chickens could be experimentally produced by feeding the embryonated eggs of the nematode, Heterakis papillosa. They had frequently encountered protozoa in the cultures in which the ova were developing, and it was considered advisable to determine whether or not these organisms represented some stage of the protozoon responsible for the disease. These results led the writer to make a careful study of the protozoan fauna encountered in Heterakis, as well as in the embryonated egg cultures. These investigations disclosed nothing of importance concerning blackhead, but the amoebae studied revealed a number of new and interesting cytological and life history characters. The best method for obtaining the amoebae under discussion consists in removing adult Heterakis from the ceca of a variety of healthy chickens. The worms are thoroughly washed in sterile physiological salt solution, and sedimented several times. They are then cut up and the material incubated in physiological salt solution for fifteen to thirty days at room temperature. During the summer of 1920, nineteen cultures were thus prepared from different lots of chickens. On examining incubated Heterakis cultures in from two to three weeks, it was found that besides worm fragments, embryonated Heterakis ova, and bacteria, the cultures nearly always contained the trophozoites and cysts of amoebae. Two species were found in the salt solution cultures either together in the same culture or separately in different cultures. The amoebae were easily recognized, particularly the cysts resting on the bottom of the Petri dish, but when the writer was in doubt, he placed a worm fragment under the microscope. Such a fragment usually proved to contain many amoebae which probably