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400 aid of the microscope. The difficult task was performed to the entire satisfaction of Nägele, who took occasion to express it in a peculiar manner. As Moleschott was returning for the first time from clinical practice in the lying-in hospital, for which he had paid the required fee to the secretary, Nägele accompanied him, and, as they were going downstairs, stuck the amount of the fee into Moleschott's vest pocket with the remark, "Clericus clericum non decimat (Clergy does not take tithes of clergy)."

In 1844 the Teyler Society of Harlem offered a prize for the best dissertation on Liebig's theory of the nutrition of plants, which formed the basis of his application of chemistry to agriculture, and which at that time excited as lively discussion in the scientific world as did Darwin's theory of the origin and evolution of species fifteen years later. Moleschott took a deep interest in the subject and was urged by Delffs to compete for the prize, which was also awarded to him. His dissertation contained a thorough examination and keen analysis of Liebig's views, and pointed out some instances of hasty generalizations and unwarranted conclusions. Moleschott exposed these logical fallacies and showed how largely they entered into the reasoning and vitiated the deductions of the distinguished chemist. The copy of the prize essay sent to Liebig was accompanied by a note in which Moleschott, while venturing to criticise his views, expressed the warmest admiration and enthusiasm for his personal character and scientific achievement. Liebig replied, thanking him for the essay, and added: "So far from being offended by opposition, I desire it, since it serves to separate the grain from the chaff"; and I have all the more reason to be satisfied when this is done, as in your case, in a clever and gentlemanly manner."

On January 22, 1845, Moleschott passed his examination, and was promoted to the degree of Doctor of Medicine, receiving the first rank. But in order to practice his profession in Holland it was necessary to have a certificate of proficiency also from a Dutch university. For this purpose he went to Leyden, where he passed the so-called colloquium doctum, which consisted in a pleasant conversation with professors of the medical faculty—Broers, Pruys van der Hoeven, and Suringar—on the endemic diseases of Holland. He then established himself in Utrecht.

In connection with Donders and a Jewish physician. Van Deen (afterward professor in the University of Groningen), Moleschott founded a scientific journal for the publication of the latest researches made by Hollanders in anatomy and physiology, to which Mulder, Harting, Jansen, Van den Broek, Kees Verloren, Eduard von Baumhauer, and others sent valuable contributions. Notwithstanding the congeniality of many of his associations and his interest in these investigations, he was not contented with his life and