A young German doctor had come to Pasteur's laboratory in order, he said, to become familiar with French microbiology. He was a student of Koch's. At Koch's 'institute' microbes were cultivated on slices of potato. Such was not the custom on the Rue d'Ulm. In order, no doubt, to know better the procedures of the latter laboratory, our German maintained he would do only that which was done in the former laboratory. Someone said to him: "That's no problem. Cultivate your bacilli as you prefer. Here are some potatoes." "But where is the knife to pare them?" "Take the first knife you come across, and if you don't find any, buy a pocket knife you come across, and if you don't find any, buy a pocket knife in the market for thirteen sous." "In Berlin, we have a special knife for paring potatoes." And our doctor would not begin his researches until he had received from Koch's laboratory that sacred instrument for paring potatoes. In such a fashion this knife came to rank as part of the scientific method.
Pierre Duhem, German Science, John Lyon, tr. (La Salle, Illinois: Open Court, 1991) p. 65.
Incidentally, that's one of the nice things about German Science, which collects together lectures originally given in Spring of 1915 to the Catholic Association of Students at the University of Bordeaux. Where else can you read a text in philosophy of science by one of the greatest philosophers of science in history that is both exceptionally readable (being intended as popular wartime lectures for students) and has jokes about Germans? Here's another:
When he no longer understands himself, the German is convinced he has finally attained the heights of metaphysics. (p. 67)
And a more bitter one:
For example: in times of war, the fancy enters his mind to massacre inoffensive beings? He sets forth this postulate: Everything that tends to shorten the duration of war is humane. Then, after having unrolled several quite conclusive syllogisms, he robs, violates, pillages, burns, executes, and torpedoes with the serene conscience of a benefactor of humanity. (p. 56)