Following fifteen years of service at the lead of the Würzburg laboratory, Külpe also established first-rate psychological institutes at the University of Bonn and the University of Munich. It was his innovative experimental psychology methods and success in establishing these psychological institutes that led to Külpe being referred to as the second founder of experimental psychology on German soil. Though Külpe and Wundt differed on matters of principle, Külpe regarded Wundt highly and published three tributes to him. In his later years, Külpe began to focus less on psychological issues and more on his interests in philosophical problems such as esthetics, where it seemed his true passion lay. Just before the Christmas of 1915, Külpe suffered a bout of influenza. He recovered to the point where he was able to return to his university teachings. He was, however, suffering from a heart infection, which he succumbed to on 30 December, after a few days of illness. It was said that had he lived longer, Külpe likely would have accepted the request to succeed Friederich Jodl and establish a psychological laboratory at the University of Vienna as well.