It is well known that the r>arasite, E. tenella, localizes in the epithelium of the cecalrouches in the chicken, but is found rarelv in other rarts of the digestive tract.There is, however, little information in to this roint>so that the presentobservations were carried out in order to zet further evidence regarding to the organ specificity of the infection of E. tenella, with the following results :l. According to the preliminary observations on passage of ingesta throughthe tract with markers (charcoal or Lycopodium used), it was found that some ofthe feed first ingested reached the entrance of the ceca within about 1 hour afterfeeding and one part could be slightly detected in the cecal lumen within 2 hoursand more markedly about 3 hours later. It required about 2 -3 days for the disap-pearance of the marker, which had entered into the ceca, from the cecal contentsor droppings up to the undetectable level.2. As the mechanism for the evacuation of cecal contents is unknown, obser-vations were carried out on chickens kept under the normal condition in thelaboratory with natural light and the report by HERRICK et al. (1947) was confirmed.The following results were obtained : a) the average daily droppings of cecalpassage by chickens were 3 -4, but no cecal droppings during the night from thesleeping time (7 -8 p.m.) to natural awakening the next morning (4 -5 a.m.).Two peaks, morning (5 -7 a.m.) and afternoon (3 -7 p.m.), appeared in the cecalevacuations without the effects due to the administration of food and water.The morning peak was more abrupt, but the afternoon peak was larger and moresluzuish. On the contrarv to the cecal dror>rinzs, the intestinal were alwavsevacuated throughout the day and night, indicating no definite peak of passage.Further attempts were carried out to ascertain the possible eflects of naturallight and the body movement of the chicken on the passage of both cecal andintestinal droppings. In the the case of the chickens deprived of natural light bykeeping them in a dark room, no cecal droppings passed during the day and night.On the other hand, in the case of the chickens kept in a cage with normal naturallight but allowing only the head and neck to be free for the purpose of suppress-ing the movement of the whole body, with such a posture as that when beeingasleep, the intestinal droppings but not t From these results it was suggested that the organ specificity of the infectionof E. tenella in the chicken might be, essentially, rather dependent upon the closeaffinity that exists between the host cell and the parasite, than to the characteristiccontents of the ceca and its retention there, though the lattter factors do notnecessarily mean that they play no role in the infection as discussed before.However, it seemed probably that the lower part if the intestine and rectum, seemingly less suitable for the growth of the coccidia, significantly changed inorder to become suited for its development under certain conditions. The mechanismfor the specificity and the change of the parasitic distribution remains unknown andawaits a solution by the further experimental evidence.

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