Charming anecdotes of the signs the Prince gave of interest in the lectures went about and had their due effect. Towards the end of one course on Nature Study (for Klaus Heinrich attended these courses also "for general information") the Professor, by way of illustration, had filled a metal shell with water and announced that the water, when frozen, would burst the shell by expansion; he promised to show the class the pieces next lecture. Now he had not kept his word on this point at the next lecture, probably out of forgetfulness: the broken shell had not been forthcoming--Klaus Heinrich had therefore inquired as to the result of the experiment. He had joined in asking questions of the professor at the end of the lecture, just like any ordinary student, and had modestly asked him: "Has the bomb burst?"--whereupon the Professor, full of embarrassment at first, had then expressed his thanks with glad surprise, and indeed emotion, for the kind interest the Prince had expressed in his lectures. Klaus Heinrich was honorary member of a student's club--only honorary, because he was not allowed to fight duels--and once or twice attended their wines, his Stürmer on his head. But since his guardians were well aware that the results the influence of strong drink had on his highly strung and delicate temperament were absolutely irreconcilable with his exalted calling, he did not dare to drink seriously, and his comrades were obliged on this point too to bear his Highness in mind. Their rude customs were judiciously limited to a casual one or two, the general tone was as exemplary as it used to be in the upper form at school, the songs they sang were old ones of real poetry, and the meetings were, as a whole, gala and parade nights, refined editions of the ordinary ones. The use of Christian names was the bond of union between Klaus Heinrich and his corps brothers, as the expression and basis of spontaneous comradeship. But it was generally observed that this use sounded false and artificial, however great the efforts to make it otherwise, and that the students were always falling back unintentionally into the form of address which took due notice of the Prince's Highness.