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SYNOPSIS. In young first generation schizonts of E. bovis, the nuclei appeared to have a random distribution. In calves killed 8 days after inoculation some of the schizonts had the nuclei arranged in a single layer at the periphery, with a few infoldings of this layer into the interior. In further development, such ingrowths of the nuclear layer resulted in the formation of compartments of varying size. In schizonts of calves killed 12 days after inoculation spherical or ellipsoidal bodies (blastophores), about 5–20 μ in diameter with a single peripheral layer of nuclei were formed. Merozoites developed as radial outgrowths from the blastophores, leaving residual bodies of variable size, which later disappeared. The response of the host cell to the presence of the schizont was characterized by marked growth of both the nucleus and cytoplasm. The nucleolus became greatly enlarged, and the chromatin was distributed in relatively fine granules. In the host cell cytoplasm, 2 concentric layers were observed; the inner was more dense than the outer. After growth of the schizont was completed its host cell was stretched into a thin covering layer about 1 μ thick. In some schizonts, the host cell disintegrated, and the schizont was then invaded by eosinophils, macrophages and other cells, which eventually destroyed the merozoites.

This paper is the second of a series reported from the Utah Station on the transfer of dietary DDT to eggs and poultry tissues. The first paper was reported by Bryson et al. (1950) on the accumulation of DDT in poultry products. The published literature on this topic has been reviewed and reported by Bryson et al. (1950). EXPERIMENTAL THE alfalfa hay fed in this experiment was from the same field described by Harris et al. (1949). This alfalfa was dusted with 0, 1, 2, and 4 pounds of technical DDT per acre. The harvested hay was ground into meal and 15 percent of this meal was included in the laying mash. DDT was also added to a similar mash made from untreated alfalfa meal at levels of 0, 50, 100, and 200 p.p.m. These diets are reported in Table 1. The design of this experiment is as follows: A . . .

Summary Three experiments were conducted to determine whether schizonts of E. bovis are appreciably influenced by the immune reaction in calves. Each experiment involved two groups each of four to six calves. Each calf in one group was given an immunizing inoculation of 60,000 to 100,000 oocysts, and after 30 to 35 days each calf in both groups was given a challenging inoculation of 800,000 to 5 million oocysts. One calf in each group was killed on successive days beginning 15 to 17 days after the second inoculation. Numbers of schizonts in the small intestine were estimated by examination with a dissecting microscope and frequency of sexual stages in the cecum and colon was observed in sections. No consistent difference was found in concentration, estimated total number, or size of schizonts in the two groups, although non-immunized calves had a much higher frequency of sexual stages. The results indicate that the schizonts and preceding stages are not appreciably influenced by the immune reaction, so that immunity must chiefly affect the merozoites or sexual stages.

Eimeria auburnensis was described by Christensen and Porter (1939) from oocysts found in fecal samples from calves from Alabama, Maryland, and Montana. In one calf, discharge of E. auburnensis oocysts was observed to occur chiefly 24 to 27 days after inoculation with 8,000 sporulated oocysts of this species and diarrhea occurred from 9 to 13 days after inoculation. To the best of our knowledge, no other observations on the life cycle of E. auburnensis have been made. Over the last 15 years, one of us (D.M.H.) has occasionally observed in tissue sections coccidia suspected of belonging to this species. When an opportunity arose, experimental studies on E. auburnensis were begun for the purpose of obtaining information about the endogenous stages of the life cycle of this species and its effect on the host.

SLATER, ROBERT L., DATUS M. HAMtVOND, AND MERTHYB L. MINER. 1970. Eimeria boris: Development in Calves Treated with Thiamine Metabolic Antagonist (Amprolium) in Feed. Trans. Amer. Microsc. Soc. 89: 55-65. Fifty-seven calves about 2 to 3 months old were used in four experiments, in each of which each calf was given 50,000 Eimeria bovis oocysts by means of a nippled flask. In three experiments, 2 groups each of 3 or 4 calves were treated with 25 and 5 mg/kg of a thiamine metabolic antagonist (amprolium) respectively, and one group was not treated. In the fourth experiment, an additional group of calves was treated with 1 mg/kg of amprolium. The amprolium was given once daily in the morning grain feeding for 21 days beginning on the day before inoculation. In three of the experiments, 1 or 2 calves in each group were killed 14 to 19 days after inoculation to determine the effect of ainprolium upon the endogenous stages of E. bovis. In the calves treated at 25 mg/kg and at 5 mg/kg, little or no clinical signs of coccidiosis were observed and only a few or no oocysts were discharged. The oocyst discharge occurred 4 to 7 days later than normal in the calves treated at 25 mg/kg. Treatment at 1 mg/kg was not effective. Coccidia were found in the tissues in calves killed 14 to 19 days after inoculation. Sixty-four of 81 schizonts found in calves treated at 25 mg/kg appeared to be retarded in development. Only 7 of 30 schizonts seen in the calves treated at 5 mg/kg and killed 14 to 19 days after inoculation showed such a retardation. These retarded schizonts were about the size and stage of development normally occurring in calves killed 8 to 10 days after inoculation. In the calves treated at 25 mg/kg, most of the host cells harboring retarded schizonts were excessively hypertrophied and some showed vacuolization. Evidence of degeneration of the schizonts was seen in these treated calves, especially those killed 19 (lays after inoculation. Under the conditions of these experiments, amproliium evidently affected the first-generation schizonts, causing many of theml to be retarded in development or to fail to develop beyond the early stages.