Ernst Haeckel and his assistant Miklucho-Maclay
at Lanzarote, in the Canaries, 1867.
In October, 1866, Haeckel had a companion in a teacher from Bonn, Richard Greeff (afterwards professor of zoology at Marburg). They took ship from London to Lisbon, where they were long detained for quarantine, though the annoyance was somewhat relieved by the discovery of an interesting medusa in the brackish water of the Tagus. They then went to Madeira and Teneriffe, not right into the tropics, but where they might get a breath of it, as it were. Two of Haeckel’s pupils, who both became well known afterwards, Miklucho-Maclay and Fol, were with them. Greeff has given a full account of the journey in a whole volume (published at Bonn, 1868), and Haeckel has written of it in two articles, one of which (in the fifth volume of the Zeitschrift der Gesellschaft für Erdkunde, Berlin, 1870) is a perfect masterpiece of narrative and description of scenery. After a long search they chose as the best station for studying marine animals, especially the medusæ, the little island of Lanzarote, instead of one of the chief islands. Here they fished and drew, in the manner taught by Johannes Müller, for three months, from December, 1866, to February, 1867. It is not exactly an ideal place. “Imagine yourself dumped down on the moor!” Haeckel said afterwards in his description of it. A piece of arid land that looked like a strip of the Sahara in the middle of the ocean. There is hardly any water, and the vegetation is correspondingly meagre. Across the middle of the island stretches a chain of volcanic craters, and old lava-fields run down from them as far as the coast. Everything of zoological interest in the place was to be found in the sea. There they found abundance. As in Messina, certain local currents drove the rich animal plancton together until there were literally rivers or streets of tiny animals. One had only to dip in one’s nets and glasses, and bring up whole shoals with every drop of water.
Haeckel had come chiefly to study the medusæ. But this led him on much further to a great zoological problem. In his General Morphology he had expounded his brilliant ideas on the subject of individuality, and now he encountered in the flesh one of the greatest marvels of animal individuality. He had shown how the higher individual is always made up of a community, a kind of state, of lower individuals. In the simplest instance there are the cells. Each of them is an individual. Millions of these individuals, banded together with division of labour for great collective operations, make up the human frame, and therefore the human “individual.” In the same way others form a beetle, a snail, or a single medusa. Sometimes, however, these higher individuals enter in turn into social combinations to form still higher communities. Human beings form social commonwealths, with division of labour among the individuals. Bees and ants form their communities in the same way. But in the latter cases the texture of the community seems to be much looser than in the preceding one. It is not so easy for the imagination to grasp a human commonwealth or a colony of bees as a real “over-individual.” It is, therefore, extremely instructive to find that at least one animal community of this kind is of so firm a texture that even on the most superficial examination it is recognised at once as an individual. This is found in one of the groups of the medusæ, the siphonophores, or social medusæ.
A number of single medusæ, each of which corresponds to what we regard as the individual man, combine and form a new body, a social individual. As citizens of this new state they have introduced the most rigid division of labour. One medusa does nothing but eat, and it thus provides nourishment for the rest, as they are all joined in one body. Another accomplishes the swimming movement; another has been converted entirely into a reproductive organ. In a word, the whole has become a “unity” once more, equipped with its various organs like any large body. Sometimes thousands of separate medusæ enter into the structure of one of these wonders of the deep. And as each of the medusæ is generally a very pretty, flower-like creature, the social groups with their charming colours look like floating garlands of flowers made of transparent and tinted crystal. Their beauty would soon fix Haeckel’s attention, but their bearing on his theory of individuality would give them an even greater value. For several years he had searched most attentively in the animal world for these “over-individuals” of the highest class. In the morphology he had had to be content with an old illustration of something of the kind, the star-fish. It was supposed to be a combination of vermalians. In this case the hypothesis has broken down, though there was a good deal to be said for it at first, and it was abandoned by him afterwards. But now, when he saw enormous numbers of siphonophores in the animal streams at Lanzarote, he entered upon a decisive study of the meaning of these real “social animals.” A social medusa has so great an appearance of unity that those who discovered it first did not believe it was a community, but a very complicated individual medusa. Vogt (1847) and Leuckart (1851) had denied this, and declared it to be a social group. But the controversy was still going on, as there was much difference of opinion as to the meaning of “social” and “state.” Haeckel now succeeded at Lanzarote in tracing for the first time the development of one of these siphonophores from the ovum. He was able to show that from the ovum only a single simple medusa is developed. This, then, becomes the parent of the community; it produces the rest of the members, not by a new sexual generation, but by budding out from itself, until the whole garland of connected individuals is ready to constitute the new over-individual, or the community. These luminous investigations were published three years afterwards (1869) in a work that was crowned by the Utrecht Society of Art and Science (The Embryology of the Siphonophoræ, with fourteen plates, published at Utrecht). But Haeckel returned time after time in later years to this group of animals with such great philosophic and zoological interest. When he had put before him in the eighties the whole of the siphonophores brought home by the splendid Challenger expedition, he combined the material with the results of his own studies in a fine work, which was included (in English) in the publications of the Challenger series at London, as the 28th volume of the Zoology of the Challenger, 1888. The voluminous work is illustrated with fifty masterly plates, some of them coloured, by Haeckel himself. The most important part of the text was also published in German at Jena, with the title, System of the Siphonophoræ. There is a good popular account of the siphonophore question in his lecture on “The Division of Labour in Nature and in Human Life” (1869). A few of these beautiful forms are also given on coloured plates in his illustrated work, Art-forms in Nature. Every thoughtful man ought, whatever his position is as regards Haeckel’s ideas, to glance at this material that he has so vigorously and clearly presented.
While he was conducting this research into the embryonic development of the siphonophores, Haeckel made certain experiments on phenomena that have lately been made the subject of a special “experimental mechanical embryology” by some of his pupils, particularly Professor Roux, of Halle. He cut up siphonophore ova into several pieces at the commencement of their development, and saw an incomplete social medusa develop from each fragment.
A Siphonophore
(Disconalia gastroblasta.)
Thus the journey, like the earlier one to Messina, brought the indefatigable student into touch once more with a “philosophical animal.” This alone would have made it well worth the trouble. How many more of the kind the future might still have in reserve for him! In the quiet months at Puerto del Arrecise, on Lanzarote, he was gradually restored to his spiritual balance. Nature had taken much from him, but she offered him an inexhaustible return. His elasticity and vigour of frame had been restored before he left Teneriffe. In a twenty-two hours’ tour, only interrupted by two hours’ sleep, he had climbed to the highest summit of the Peak, in such an unfavourable season (in the November snow) that the native guides would not go any further in the end; all those who were with him except one stopped short a little way from the top. The short rest at the summit (4,128 yards above the sea-level, on the icy edge of the crater) was greatly enjoyed by him. He could see over a distance of 5,700 square miles, as much as one-fourth of the whole of Spain. “The extraordinary range and height of the horizon gives one a vague idea of the infinity of space. The deep unbroken silence and the consciousness that we have left all animal and vegetal life far behind, produce a profound feeling of solitude. One feels oneself, with a certain pride, master of the situation that has been secured with so much trouble and risk. But the next moment one feels what we really are—momentary waves in the infinite ocean of life, transitory combinations of a comparatively small number of organic cells, which, in the last resort, owe their origin and significance to the peculiar chemical properties of carbon. How small and mean at such moments do we find the little play of human passions that unfolds itself far below in the haunts of civilisation! How great and exalted in comparison does free Nature seem, as it unrolls before us, in one vast picture, the whole majesty and splendour of its creative power!” Thus he himself describes the moment. Something of that feeling of exalted solitude entered into his life. He stood firm and undazed—come what might.