The absorption of oxygen and the elimination of carbon dioxide in the lungs take place by diffusion alone. There is no trustworthy evidence of any regulation of this process on the part of the organism.

The theory of the lung as a gland has justified its existence and done excellent service in bringing forward facts, which shall survive any theoretical construction that has been or may hereafter be put upon them.

We may fondly imagine that we are impartial seekers after truth, but with a few exceptions, to which I know that I do not belong, we are influenced—and sometimes strongly—by our personal bias; and we give our best thoughts to those ideas which we have to defend.

When experimental results are found to be in conflict with those of an earlier investigator, the matter is often taken too easily and disposed of for an instance by pointing out a possible source of error in the experiments of the predessessor, but without enquiring whether the error, if present, would be quantitatively sufficient to explain the discrepancy. I think that disagreement with former results should never be taken easily, but every effort should be made to find a true explanation. This can be done in many more cases than it actually is; and as a result, it can be done more easily by the man “on the spot” who is already familiar with the essential details. But it may require a great deal of imagination, and very often it will require supplementary experiments.

It is rare enough that a scientist sheds light on an area which nature has kept secret and then during his lifetime, sees that area illuminate in turn every corner of physiology and medicine. It is rarer still that one man can contribute concurrently almost as much to several other biological fields as well. That meanwhile he [August Krogh] should develop in addition a large school of devoted students who loved the man even more, if possible, than they venerated the scientist, spells the highest form of genius.