Pierre-Joseph van Beneden, Belgian paleontologist, zoologist.
Aquarium et musée de zoologie, Liège, Belgium
Statue of Édouard van Beneden in front of the “Aquarium et musée de zoologie”, Liège, Belgium, inaugurated 1920. Sculptor: Pierre Braeke (1859-1938).
Edouard was appointed a professor at the University of Liège in 1870 with the qualification of chargé de cours and was promoted to ordinarius in 1874.
His scientific work is characterized by a great unity resulting from the character of the problems to which he devoted his attention. In 1872 Van Beneden went to Brazil, and from there he brought back a number of specimens, particularly Annelida, which were studied by Armauer Hansen. P. J. Van Beneden had organized a modest laboratory on the Belgian sea coast at Ostend, and there Edouard had the opportunity to collect and study many specimens of fauna, particularly from Thornton Bank, near Ostend.
In a paper on the origin of the sexual cells of hydroids (1874), Van Beneden showed, besides great care in observation, his tendency to sometimes bold generalization. At that time, the gastrula theory of metazoan development was presented by Huxley, Lankester, and Haeckel; Van Beneden suggested that ectoderm and endoderm have opposed sexual significance, the ectoderm being the male layer and the endoderm the female layer. He thereafter recognized the hermaphrodite nature of the egg, an idea he later developed in his studies on cestodes.
Van Beneden’s first publication on dicyemida dates from 1876. He made a thorough and careful study of their structure and observed that they derive from an epibolic gastrula, the hypoblast of which is formed by a long, central single cell. In 1877 he proposed the creation of the phylum Mesozoa, considering it an ideal transition between monocellular and multicellular animal forms. This idea, after a temporary eclipse, has regained popularity.
In 1864, by the application of the embryogenetic method and the biogenetic law, Kovalevski had shown, to everyone’s surprise, that tunicates were chordates. They, therefore, were an excellent material for studies in comparative morphology, with a view to establishing their phylogenetic relations with other animals.
In collaboration with his colleague Charles Julin, Van Beneden published in 1887 an important paper on tunicate morphology in which they stated that the mesoblast derives from the enterocele. They also accepted that the cardiopericardic vesicle and the epicardia derive from common forms, the procardia, which they considered to be pharyngeal diverticula.
Van Beneden pursued these studies until his death and left notes that have been published by his disciple Marc de Selys-Longchamps, who, from drawings left by his master, concluded that the endoblast is not derived from the enterocele and showed that the pericardium of tunicates is the ultimate remainder of the chordate celom.
In his papers on the maturation and fertilization of the egg of Ascaris megalocephala, the first of which was published in 1883, he revealed the essential nature of fertilization: the union of two half-nuclei, one female and the other male. He showed that in Ascaris, it is not until the male and female pronuclei have formed what we now call chromosomes (which are accurately represented in his plates) that the respective nuclear membranes break down. He described how each set of chromosomes moves to the equatorial plate. Van Beneden saw that in the variety of Ascaris he called univalens, which had only two chromosomes, each parent contributes one chromosome to the pair found in the zygote. Through this discovery, the individuality of the single chromosome was first demonstrated.
Van Beneden’s opinion on the mechanism of karyogamie reduction, which he had discovered, was that of the four chromosomes of bivalens, two entered the first polar body and two remained to form the female pronucleus. It was shown independently, by Theodor Boveri in 1887-1888, and by Oscar Hertwig in 1890, that the real nature of the “maturation” division leading to the formation of ripe gametes in both sexes is that each chromosome in the mother cell divides once, while the cell itself divides twice. In 1892 Boveri showed, in Ascaris megalocephala bivalens, that two of the eight daughter chromosomes of the egg’s mother cell go into each of four cells: into each of the three polar bodies (if the first polar body divides after being given off) and into the ovum.
In a paper published in collaboration with the photographer Neyt (1887), Van Beneden described the centrosome and showed that it was a permanent cell organ which remained in the cell during the resting period and divided into two parts before the beginning of the next mitosis.
From the beginning of his scientific work, Van Beneden had been preoccupied with the problem of the origin of vertebrates. His first interpretation of the didermic mammalian embryo was immediately accepted, but in 1888 he concluded a study of the gastrulation of mammals that became a classic only after his death.
Edouard Van Beneden's main interests were directed toward the animal groups his father had studied: protozoa, hydraria, cestodes, nematodes, and tunicates. Later he extended these studies to dicyemida, and later to vertebrates, particularly mammals.
Quotes from others about the person
“"During the half-century that has elapsed since the enunciation of the cell-theory by Schleiden and Schwann, in 1838-39, it has became ever more clearly apparent that the key to all ultimate biological problems must, in the last analysis, be sought in the cell. It was the cell-theory that first brought the structure of plants and animals under one point of view by revealing their common plan of organization. It was through the cell-theory that Kolliker and Remak opened the way to an understanding of the nature of embryological development, and the law of genetic continuity lying at the basis of inheritance. It was the cell-theory again which, in the hands of Virchaw and Max Schultze, inaugurated a new era in the history of physiology and pathology, by showing that all the various functions of the body, in health and in disease, are but the outward expression of cell-activities. And at a still later day it was through the cell-theory that Hertwig, Fol, Van Beneden, and Strasburger solved the long-standing riddle of the fertilization of the egg, and the mechanism of hereditary transmission. No other biological generalization, save only the theory of organic evolution, has brought so many apparently diverse phenomena under a common point of view or has accomplished more far the unification of knowledge. The cell-theory must therefore be placed beside the evolution-theory as one of the foundation stones of modern biology." — Edmund Beecher Wilson”