In these many years beginning, I would say, right after my PhD thesis where I did, at [Erwin] Stresemann's suggestion, an analysis of the so-called snowfinches… that was 1926, ‘27. From there until my very most recent ornithological papers I constantly worked with birds and made discoveries one after the other. Now the… one of the most basic contributions that I made was when working up the material of the Whitney and Rothschild collections, I took one genus after the other of birds and revised it. I established how many species there were, how many subspecies could be recognized, what was the distribution, what names are not valid, are synonyms or others, and I did this for many… for many groups. This was the first time this had been done since the 1880s or 1890s, and… I don't whether I should be happy about this or unhappy, but in most cases my analysis was so definitive that nobody has worked on these genera since, and… and nobody has ever claimed that… that what I had done was wrong… and it might have been wrong, how do I know? In the course of these studies I discovered 25 new species of birds and over 400 new subspecies. And… I… made the… I was the first one to clearly state that various groups of birds like the Australian flycatchers, warblers, shrikes, nuthatches, creepers, which are… have… have always been associated with the Asiatic or European birds with the same vernacular name, were not all related to them, but were endemic Australian elements. At the time I had no way of determining to which other Australian birds they might be most closely related. This is something that later on Charles Sibley established by using molecular methods, but I don't think he ever mentions that I… a good many years before him, had already established that these were not northern elements but… autonomous Australian elements.