Jean André de Peyssonnel was born at Marseilles in 1694. He was a student of medicine and natural history at Paris when the Académie des Sciences charged him with the task of studying the coral on the sea-shore. Peyssonnel began his observations in the neighbourhood of Marseilles in 1723. He pursued it on the North African coast, where he had been sent on a mission by the Government. Aided by a long series of observations as exact as they were delicate, Peyssonnel demonstrated that the pretended flowers which the Count de Marsigli thought he had discovered in the coral, were true animals, and showed that the coral was neither plant nor the product of a plant, but a being with life, which he placed in the first "rung" of the zoological ladder. "I put the flower of the coral," says Peyssonnel, "in vases full of sea-water, and I saw that what had been taken for a flower of this pretended plant was, in truth, only an insect, like a little sea-nettle, or polyp. I had the pleasure of seeing removed the claws or feet of the creature, and having put the vase full of water, which contained the coral, in a gentle heat over the fire, all the small insects seemed to expand. The polyp extended his feet, and formed what M. de Marsigli and I had taken for the petals of a flower. The calyx of this pretended flower, in short, was the animal, which advanced and issued out of its cell."
The observations of Peyssonnel were calculated to put aside altogether theories which had lately attracted universal admiration, but they were coldly received by the naturalists, his contemporaries. Réaumur distinguished himself greatly in his opposition to the young innovator. He wrote to Peyssonnel in an ironical tone: "I think (he says) as you do, that no one has hitherto been disposed to regard the coral as the work of insects. We cannot deny that this idea is both new and singular; but the coral, as it appears to me, never could have been constructed by sea-nettles or polyps, if we may judge from the manner in which you make them labour."
What appeared impossible to Réaumur was, however, a fact which Peyssonnel had demonstrated to hundreds by his experiments at Marseilles. Nevertheless, Bernard de Jussieu did not find the reasons he urged strong enough to induce him to abandon the opinions he had formed as to their vegetable origin. Afflicted and disgusted at the indifferent success with which his labours were received, Peyssonnel abandoned his investigations. He even abandoned science and society, and sought an obscure retirement in the Antilles as a naval surgeon, and his manuscripts, which he left in France, have never been printed. These manuscripts, written in 1744, were preserved in the library of the Museum of Natural History at Paris. The title is comprehensive and sufficiently descriptive. It should be added, in order to complete the recital, that Réaumur and Bernard de Jussieu finally recognized the value of the discoveries and the validity of the reasoning of the naturalist of Marseilles. When these illustrious savants became acquainted with the experiments of Trembley upon the fresh-water hydræ; when they had themselves repeated them; when they had made similar observations on the sea anemone and alcyonidæ; when they finally discovered that on other so-called marine plants animalcules were found similar to the hydra, so admirably described by Trembley;—they no longer hesitated to render full justice to the views of their former adversary.
While Peyssonnel still lived forgotten at the Antilles, his scientific labours were crowned with triumph at Paris; but it was a sterile triumph for him. Réaumur gave to the animalcules which construct the coral the name of Polyps, and Coral to the product itself, for such he considered the architectural product of the polyps. In other words, Réaumur introduced into Science the views which he had keenly contested with their author. But from that time the animal nature of the coralline has never been doubted.
Fig. 47. Living Bed of Coral after the entrance of the Polyps.
(Lacaze-Duthiers.)
Without pausing to note the various authors who have given their attention to this fine natural production, we shall at once direct our attention to the organization of the animalcules, and the construction of the coral.
M. Lacaze-Duthiers, professor at the Jardin des Plantes of Paris, published in 1864 a remarkable monograph, entitled "L'Histoire Naturelle du Corail." This learned naturalist was charged by the French Government, in 1860, with a mission having for its object the study of the coral from the natural history point of view. His observations upon the zoophytes are numerous and precise, and worthy of the successor of Peyssonnel; but for close observation, practical conclusions, and popular exposition, the world is more indebted to Charles Darwin than to any other naturalist.
A branch of living coral, if we may use the term, is an aggregation of animals derived from a first being by budding. They are united among themselves by a common tissue, each seeming to enjoy a life of its own, though participating in a common object. The branch seems to originate in an egg, which produces a young animal, which attaches itself soon after its birth, as already described. From this is derived the new beings which, by their united labours, produce the branch of coral or polypidom.