word “plancton” (swimming matter) has been substituted for his phrase. As we now send whole expeditions over the seas to study “plancton,” the word has found its way into ordinary literature. The regular anglers who were then in Heligoland must have looked on this subtle work with a butterfly net as a sort of pleasant joke born from the professional brain. The young student must have made an impression on them with his vigour, though he had not yet turned himself into a marine mammal, living half in the water for days together. They called him a “sea-devil.” What pleased the master most in him was the talent he already showed of quickly sketching the tiny, perishable creature from the surface of the sea while it was fresh. Haeckel had been passionately fond of drawing from his early years. Now the old bent agreed with the new zeal for zoology. “You will be able to do a great deal,” Müller said to him. “And when once you are fairly interested in this fairy-land of the sea, you will find it difficult to get away from it.” The dream of Messina, that Gegenbaur had conjured up, seemed to draw nearer. [Illustration: FISHING IN HELIGOLAND IN 1865. Anton Dohrn (Naples). Richard Greeff (Marburg). Ernst Haeckel (Jena). Max Salverda (Utrecht). Pietro Marchi (Florence). ] These lively days at Heligoland provided Haeckel with the material for his first little zoological essay. It dealt with the development of the ova of certain fishes (_On the Ova of the Scomberesoces_, published in Müller’s _Archiv_ for 1855). Müller lent him ova from the Berlin collection to complete his study. It is the same volume of the _Archiv_ in which, in Reichert’s introduction, the great controversy breaks out over Virchow’s pregnant assertion that each human being is a state composed of millions of individual cells. Haeckel remained with Müller at Berlin for the whole winter, and was drawn more and more into the province of comparative anatomy, or, to speak more correctly, zoology. The official Professor of Zoology at Berlin at the time was really the aged Lichtenstein, who had occupied the chair since 1811. Haeckel has humorously described himself in later years as self-taught in his own subject, saying that he had attended many most excellent colleges, but never visited an official school of zoology. The only opportunity to do so at the time was under Lichtenstein, but that professor bored him so much that he could not attend his lectures. Lichtenstein was a venerable representative of the old type of zoologist; his ideal was to give a careful external description of the species on the strength of specimens chosen from a well-stocked museum. A whole world lay between these surviving followers of Linné and the splendid school of Johannes Müller.