We can see very well that this was quite natural. If there was any man likely to put forward such views it was Virchow. He had passed through Müller’s school, but was now one of the younger group who, even during Müller’s life, were gradually adopting certain very profound views on life and man, without any particular resistance on the master’s part. The chief characteristic of nearly the whole of this group was the lack of the volcanic stratum below of deep and personal religious feeling; in Müller this had been throughout life an enchained Titan among the rocks of his logical sense of realities, yet it had given a gentle glow and movement to the floor of his mind. Rudolf Virchow was the coolest, boldest, and clearest-minded of the group. He went to the opposite extreme. If Müller was standing on a volcano, which he only repressed by the giant force of his will—a nature that was above all master of itself—Virchow, on the contrary, was standing on a glacier, and he had never taken the trouble to conceal it. I should not venture to count him amongst the instinctively Monistic minds, in the sense of Goethe, to whom the unity of God and nature, the inorganic and the organic, the animal and the man, comes as an ardent and irresistible feeling. But it would have been strange if, in those years and in the middle of the whole scientific current of his time, his own organ, his icy logic, had not led him to the same conclusion; that it is a simpler method of research to believe in natural law alone, to regard the living merely as a complex play of the same forces that we have in physics and chemistry, and to consider man, with the bodily frame of an ape-like mammal, to be really such an animal. I believe, indeed, that Virchow never abandoned this simple solution in his own mind at any part of his career. The controversy he afterwards engaged in ran on different lines. It seems to me that at an early stage of his development he became convinced that there must be limits to scientific inquiry, not on logical, but on diplomatic grounds; because it is not an absolute agency, but only a relatively small force amongst many more powerful institutions, the Church, the State, and so on. Hence it would have to respect limitations that were not drawn from its own nature; in given cases it would have to keep silent in order not to jeopardise its existence as a whole. It is my firm belief that this diplomatic attitude as such would lead to the destruction of all pursuit of the truth. It carefully excludes the possibility of any further martyrdoms, but at the cost of science’s own power to illumine the world. In my opinion the free investigation of the truth is an absolute right. Churches, States, social orders, moral precepts, and all that is connected with them, have to adjust themselves to this investigation, and not the reverse.

However, the point is that under Virchow—more particularly under Virchow, in fact—Haeckel would be educated into the general attitude with regard to God, nature, life, and man, to which he has since devoted his whole energy. In spite of Goethe—and who would be likely to take Goethe as his guide in his twenty-first year?—the ardent young student was as yet by no means firmly seated in the saddle. He grubbed, and sought, and rejected. In his Riddle of the Universe he tells us that he “defended the Christian belief in his twenty-first year in lively discussions” with his free-thinking comrades, ... “although the study of human anatomy and physiology, and the comparison of man’s frame with that of the other animals, had already greatly enfeebled my faith. I did not entirely abandon it, after bitter struggles, until my medical studies were completed, and I began to practise. I then came to understand Faust’s saying, ‘The whole sorrow of humanity oppresses me.’ I found no more of the infinite benevolence of a loving father in the hard school of life than I could see of ‘wise providence’ in the struggle for existence.”

When the three terms of medical training were over, he received another impulse to his own particular interest in science. Kölliker invited him in August, 1856, to spend the two months’ holiday with him on the Riviera. It was the first Mediterranean school of zoology, though as yet only a kind of “payment on account.” On the journey he made the acquaintance of the zoological museum at Turin and its well-travelled director, Filippo de Filippi, and he saw the grandeur of the Maritime Alps on the Col di Tenda. The master, Kölliker, Heinrich Müller, Karl Kupffer (afterwards professor at Munich), and he established themselves at Nice, and fished for all sorts of creatures with the Müller-net at Villefranche. Fortunately, Müller himself happened to be visiting the Riviera at the same time, and they received a direct stimulus from him. The first result of this journey in the summer and autumn was that Haeckel secured his degree with a zoological-anatomical work, instead of with a strictly medical treatise. As he had done from Heligoland two years before, he now brought home from the Mediterranean the material for a short technical theme. He again spent the winter at Berlin to put it together. It was an histological study of the tissues of crabs, and therefore lay in the province of the articulates, an animal group, it is curious to note, which he has not entered into more fully in the course of his long and varied work as special investigator. At Nice he made a thorough study of the nerve-tubes of the spiny lobster and other available marine crustacea, and discovered several remarkable new structural features in them. At Berlin he entered upon a minute microscopic study of the common craw-fish. His dissertation for the doctorate embodied the main results of his research. It was entitled De telis quibusdam Astaci fluviatilis, and was printed in March, 1857. It appeared the same year in an enlarged form in Müller’s Archiv, with the title The Tissues of the Craw-fish. On March 7th he received his medical degree, Ehrenberg, the great authority on the infusoria, presiding. In the customary way the young doctor had to announce and defend several theses. One of them is rather amusing in view of later events.

He most vigorously contested the possibility of “spontaneous generation.” The meaning of the phrase is that somewhere or at some time a living thing, animal or plant, has arisen, not in the form of a seed or germ or sprout from a parent living thing, but as a direct development out of dead, inorganic matter. Haeckel had not made a personal study of the subject. What he said in his thesis was merely a faithful repetition of Müller’s opinion. At that time it was believed that science had empirically disproved spontaneous generation. An old popular belief held that fleas and lice were born every day from non-living dirt and dust, but that had been refuted long before. No egg, no animal: every living thing develops from an egg. This had been laid down as a fixed rule. When the microscope revealed an endless number of tiny creatures in every drop of stagnant water, in the air and the dust and the soil, it was a question whether the rule was not wrong. Surely these simplest of all living things, apparently, were born by spontaneous generation? However, the question was believed to have been settled in two ways. Schwann, the co-discoverer of the cell-theory, had made certain experiments which seem to prove directly that even these tiny beings, the infusoria and bacteria, were never formed in a vessel containing water and dead matter, if it had been carefully assured beforehand that the minute living germs of these animals that floated in the air could not penetrate into the vessel. At the same time Ehrenberg and others stoutly denied that the infusoria were the “simplest” organisms, or that they could conceivably be born in that way. They declared that the infusoria were “perfect organisms” in spite of their smallness. The belief that these tiny creatures consisted of “one cell,” and so formed, as it were, the ultimate elements of the plant and animal worlds on the lines of the cell-theory, was seriously menaced, and apparently on the way to be destroyed. Finally, the tapeworm and similar parasites had been declared to evolve by a kind of spontaneous generation from the contents of the intestines. But this also was proved to be untrue. Thus there was ample material for a solid dogma: there was no such thing as spontaneous generation. The dogma, moreover, harmonised with the prevailing belief in a special vital force and a radical distinction between the living and the dead, which was still shared in a subtle form by even a man like Müller. The dogma was formulated. Spontaneous generation was struck out of the scientific vocabulary as unscientific and a popular superstition. The young doctor, duly initiated into these ideas of the time, could not resist the temptation to give his own kick to the fallen theory. Yet how strangely things have changed since then! Two years afterwards Haeckel ceased to believe in a special vital force; he was now absolutely convinced that there were unicellular beings; his whole theory of life seemed to demand spontaneous generation as a postulate, and he even doubted the force of the experiments of Schwann and others. Haeckel himself became the keenest apostle of the theory of spontaneous generation. Whenever it is mentioned to-day, we think of the weight of his name which he has cast in the scale in its favour. So the leaves change even in the forest of science: yesterday green, to-day red and falling, to-morrow green once more. On the same branch as the dogmas we find the correctives growing, that will at length split them open and cast them as empty husks to the ground.

The history of Haeckel’s medical doctorate can be written in a few plain and touching lines. After receiving his degree he was sent by his prudent father, to keep him away from crabs and other monsters of the deep, to Vienna for a term, to do hospital work under Oppolzer, Skoda, Hebra, and Siegmund. All that we find recorded of this term is that his old love of botany revived in earnest. Immense quantities of dwarf Alpine plants were collected. When the traveller passed by the spot twenty-four years afterwards on a quiet autumn Sunday, on his way to take ship at Trieste for the tropical forests and giant trees of Ceylon, the memory of Schneeberg and the Rose-Alp came upon him like a dream. However, the hospital work, together with a short span of cramming in the winter at Berlin, must have had some effect, as he passed the State-examination in medicine. In March, 1858, he was a “practising physician.” He had in his hand the crown of prudent ambition—and he felt like a poor captive. There was one source of consolation—Johannes Müller. While one was near him there was a possibility of more real work. He discussed with him the plan of the study of the development of the gregarinæ (parasitic protozoa), which he wanted to conduct in Müller’s laboratory in the summer of 1858. Then he was stricken, like so many others, with the thunderbolt of the news of Müller’s sudden death, on April 28th of the same year. What must he do now? He began to practise. It is said on his own authority that he fixed the hours of consultation from five to six in the morning! The result was that during a whole year of this philanthropic occupation he had only three patients, not one of whom died under his earnest attention.

“This success was enough for my dear father,” says Haeckel. We can well believe it.

The kindly old man consented to one more year of quite extravagant study, in which all was to come right. It was to be a year of travel, in Italy. He was to devote himself to the study of marine animals, not merely for pleasure, but earnestly enough for him to find a basis for his life in the result. This he succeeded in doing. Like the children of fortune, who at the very moment when they cannot see a step before them make a move that the Philistine regards as the safest and last refuge, Haeckel becomes engaged that very year to his cousin, Anna Sethe. After that, in January, 1859, he goes down to the coast. He makes for the blue Mediterranean, which he already knows will prove anything but an “unprofitable sea” for him. He will conjure up treasures of science from its crystal depths with his Müller-net; then on to fortune, position, marriage, and the future. The fates have added a world-wide repute, if they have denied many a comfort.

CHAPTER III
THE RADIOLARIA

In the January of 1859 Haeckel, then in his twenty-fifth year, came to Italy with the determination “to do it thoroughly.” By the autumn the body of the peninsula had been covered down to Naples, Capri, and Ischia. The winter, until April, 1860, was spent at Messina.