For a number of years we have been struck by the absence of truly pathologic lesions as a cause of death among many of the immature infants born in the Pennsylvania Hospital. Many of these infants appeared to have died of respiratory failure, as evidenced by cyanosis and gasping respirations in the presence of seemingly normal cardiac function. In fact, it was usual for the heart to continue beating even after respirations had ceased. Numerous embryologic studies on the development of the fetal lung and the lining of the alveoli have been made ; yet in the literature there has been little discussion of the clinical significance of the results of such studies. Although death in the premature infant is undoubtedly caused by a complex mechanism which includes anatomic and metabolic dysfunction of numerous organs, it seemed desirable to make an anatomic study of the fetal lung to determine what bearing immaturity might have on respiratory failure.
MATERIAL AND METHODSTwenty-two infants who either were dead or died within twenty-two days of birth were selected for study. None of the stillborn infants were macerated and so far as could be determined, all died during labor. It was estimated that the infants, whose crown to heel measurements ranged from 15 to 53 cm., varied in age from 4 lunar months to full term. At necropsy the thoracic cavity was opened and the right main bronchus was occluded by a ligature. Through a soft rubber catheter, inserted by way of the trachea into the left main bronchus, a 10 per cent concentra¬ tion of solution of formaldehyde U. S. P. was allowed to flow by gravity until the lung filled the left thoracic cavity. The pressure of the injected fluid in no instance exceeded 20 cm. of water. As the catheter was removed the main bronchus was
