On Saturday 14 March 1931, Westerdijk celebrated the twenty-fifth anniversary of her directorship. Early in the morning, she and her mother were driven to the Badhotel in Baarn, where the entire board of the Willie Commelin Scholten Phytopathology Laboratory Foundation awaited her for the fiftieth board meeting.

Before Went opened the meeting, however, Westerdijk made him a gift of a gavel, ‘to remedy the absence of a gavel in the years behind us’, the venerable Ernst Krelage, secretary of the board, recorded gravely in the minutes. In this close circle of board members, Went then proceeded to share with his fellows some reflections which were ‘better not aired in public.’ He doubtless closed the meeting with a merry tap of his new gavel.

After lunch followed the official ceremony. Seated grandly among several lush flower arrangements and surrounded by hundreds of people who had arrived to pay tribute to her, including professors, local dignitaries, students and former students, friends and acquaintances, Westerdijk listened to Went's speech, which was interrupted half-way through by two crackling radio tributes from the Dutch East Indies. After dinner, students performed a revue in the auditorium of Baarn's Lyceum, the local grammar school. One of the highlights of the festivities was the reappearance of the traditional puppet show: former students put Punch and Judy through their paces one more time, with some idiosyncratic commentary on the guest of honour. The dancing and merrymaking went on until the early hours.

The anniversary did indeed mark the end of an era. For one thing, only Krelage, Went and Hugo de Vries, of the original founders, were still alive; the latter two were nearing the end of their careers, and both would die in the summer of 1935. After that, only Krelage, who, since the collapse of the bulb market after the First World War, had been forced to sell the firm of E.H. Krelage & Son, and whose board membership was therefore based purely on historical considerations, could bear witness to the old times. But it was the end of an era in another sense too: with Westerdijk's dual appointment as professor of phytopathology, the Phytopathology Laboratory had finally achieved its destiny as a public, university laboratory, rather than a private foundation. This transformation was accompanied by several drastic changes.