REFERENCES

respectively for the 24 and 30 percent protein lots. In case of phosphorus more was retained by the poults reported on in this paper. SUMMARY 1. Two lots of day-old "Beltsville White " poults were individually fed equal amounts of rations containing 24 and 30 percent of protein. 2. The lot fed the diet with 30 percent protein showed a greater gain in a shorter period while consuming equal amounts of feed. 3. The percentage utilization of nitro-gen, calcium and phosphorus was higher IN PREVIOUS electron micrographs of the virus of chronic respiratory disease in chickens (Tucker strain) it was demon-strated by Reagan et al. (1951) that this strain contained virus-like filaments which had an average width of 53 millimi-crons. The morphological characteristics of this strain of chronic respiratory dis-ease (CRD) of chickens appeared to be similar in size and shape to the causative agent of infectious sinusitis of turkeys. The present studies were undertaken to determine whether the causative agents of different strains of chronic respiratory dis-ease differ morphologically and whether more than one agent could be detected by electron microscopy