To the Editor: I will answer Dr. Gruenwald's criticisms one by one.
With the exception of the cases noted, all of the infants whose lungs were studied were neonates, not over two days of age.
I categorically deny that the lungs of young premature infants have no alveoli. These spaces are lined by the usual alveolar lining cells, not by columnar respiratory epithelium; they have the structure of alveoli and function as such.
I do not know what Dr. Gruenwald means by a "pseudopremature infant."
It is a well-known fact that hyaline membranes are not seen in infants less than two hours of age. Yet, as I point out, some damage to the alveolar walls must occur prior to the formation of the membranes; this damage may greatly alter the characteristics of expansion of the lung.
Regardless of the reproducibility of the curve of the