The teaching of roentgenology was given an important place on the program of the Second International Congress of Radiology at Stockholm, and as a teacher of undergraduate and postgraduate students I was especially interested in those sessions. For teaching purposes an easily available literature of all branches of knowledge concerning the X-ray would be ideal. Recently I became interested in the X-ray evidence of persistent congenital atelectasis, and I wish at this time to present two cases. Case 1 is from the service of Dr. C. G. Grulee (Hospital Case No. 238,152). This baby entered the hospital at four weeks of age, with a cold and dry cough of a week's duration. It was a premature baby which had been kept in an incubator for two weeks. The cough persisted. There was a satisfactory gain in weight. Temperature ranged from 97° to 101°. Physical examination showed no definite impairment of resonance, although fine and coarse crackling râles were heard over the base of each lung and at the angle of each scapula, posteriorly. These findings continued almost unchanged during the rest of this child's life. During the last ten days repeated attacks occurred in which the child became extremely cyanotic, with labored respiration, so that stimulants, oxygen and carbon dioxide, and artificial respiration were used. In such an attack the child died at the age of two months. The X-ray film (Fig. 1) shows a disseminated infiltration in the mesial portion of each lung, with clear periphery. The other findings are normal. The second case is from Dr. A. H. Parmelee's service (Hospital Case No. 228,633). This was a prematurely born infant, cyanotic at birth, with cyanosis of the extremities and cyanotic attacks for ten days. It was kept in an incubator for three months, during which time it gained weight slowly. In the second three months, at home, the child gained fairly well, but the mother said there was a cough, occasional colds, once apparently a pneumonia. At six months of age the child was re-admitted to the hospital as a feeding problem. For the next three months the child's condition remained substantially the same, week after week, with alternating remissions and exacerbations of temperature—daily fluctuations of one to four degrees, often up to 102, 103, or 104 degrees. The cough persisted. There was a slowly increasing weight curve, with fairly normal digestion. On physical examination, very little change was noted from week to week. The right lower lobe was definitely dull, with bronchial breathing and a few crepitant and subcrepitant riles. The left lung had definite bronchovesicular breathing, no rales, but a definite prolongation of the respiratory phase, and breathing was harsh. The clinical diagnosis was that of unresolved low grade bronchopneumonia.