In Reply.—Hebert and his associates have made useful suggestions, such as performing several additional series of control studies. Surprisingly, however, they neglected to mention a number of other controls to ascertain the possible effects of anesthesia and mechanical ventilation and point out the species difference between pigs and man.
Hebert and his coauthors took issue with several of the speculations made in our study. The possible interaction of PMIs with the AM phagocytic function was discussed in the last two paragraphs of our article, which began with "Finally, we suspect...." This is obviously only a working hypothesis that may be useful for future studies. Furthermore, our statements were misrepresented. We did not argue that the reduced phagocytic activity was the "result" of a decreased percentage of AMs. In fact, we suggested that the influx of PMLs into the atelectatic segment may play a role in the observed development of