In this study of one hundred cases the average age of the patient was thirteen years, the youngest five years, and the oldest forty-one years. Cooperation was very good; almost without exception the patients were most interested. Twelve hundred vital capacity trials were given and the four hundred highest readings recorded, giving an average of three readings per individual made at different intervals. Muscles were checked in all cases by Miss Kollman. Readings were done in the main by one person. Calculated normal vital capacity, according to standing height from Dr. Stewart's table, was used and percentage of normal vital capacity figured from this. In addition percentage of normal vital capacity, according to Dr. Myers' tables of chest circumference and surface areas, was used.
Our conclusions follow, after observation over a period of one and a half years in which physical examination, roentgen examination, laboratory, muscle check, and repeated vital capacity readings were done.