VAN TIEGHEM, PHILIPPE

(b, Balleul, Nord, France, 19 April 1839; d. Paris, France, 28 April 1914)

botany

Van Tieghem’s father, a textile merchant, died in Martinique of yellow fever shortly before the birth of his son; and his mother died immediately afterward. Philipps was their fifth child and was brought up by his uncle and aunt, and later by his sisters. He received his baccalauréat-ès-sciences at the collège of Bailleul in 1856. As a scholarship student at the lycée of Douai, he prepared for the entrance examination to the École Polytechnique but decided instead to take the examination for the École Normale Supéreriure, which he entered in 1858. After passing the agreégation in Physical and natural sciences in 1861, van Tieghem became agreégeé-preéparateur in botany and mineralogy. Under Pasteur’s supervision he prepared a dissertation on ammoniacal fermentation. Since his examiners considered that his research pertained essentially to chemistry, he was granted a doctorate in the physical sciences and not, as he had hoped, in the natural sciences. Wishing to become a botanist, he presented a second dissertation on the Araceae, which earned him the desired degree in 1867.

When Payer’s chair at the École Normale Supérieure became vacant in 1864, van Tieghem was appointed his successor. Thus, at age twenty-five, he became maître de conférences in botany. From his marriage in 1862 to HélÈne Sarchi he had four daughters and one son.

Because of the variety and the extent of van Tieghem’s 328 recorded writings, a chronological list cannot provide a true picture of his work, Throughout his life he simutanously studied several subjects: and his research covered five fields of botany: cryptogamy, fermentation, anatomy and biology of phanerogams, the application of anatomy to classification, and plant physiology.

In studying plant evolution and the reproduction of fungi, van Tieghem showed the value of using a pure culture of a single spore kept in a liquid medium. The spore must be protected from contamination by an enclosure yet remain accessible to microscopic observation. For his work on these monosperm cultures, van Tieghem was elected to the Académie des Sciences in 1877 and was appointed professor-administrator at the Muséum d’Histoire des Naturellle in May 1879.

Van Tieghem was one of the first to reveal the relationship of blue algae to bacteria. In 1878 he studied “sugar gum” and established that it was a plant that lived on sugar. He described its development and proved that the insoluble substance, an isomer of cellulose, that forms the curd of the gum is excreted by the cells of the organism, which he named Leuconostos mesenteroides.

From 1877 to 1879 van Tieghem investigated Bacillus amylobacter and butyric fermentation. He demonstrated that only the membranes (whether cutinized, suberized, or lignified) of the submerged sections of aquatic plants can resist this bacterium, the role of which in the decomposition of complex organic substances into simple ones was soon confirmed. In collaboration with Bernard Renault, van Tieghem discovered that organisms closely related to Bacillus amylobacter were present in sections of carboniferous plant tissues, where they were preserved by silicification. The two scientists thus established the possibility that coal originated through the same fermentation process occurring in the remote past.

Van Tieghem created an anatomy founded on the homologies of tissues and on their origin from the initial cells. In addition to describing the tissues themselves, he considered the modes of their origin and the pattern of thri differentiation. He distinguished three parts of the plant: root, stem, and leaf–a conception that won widespread acceptance largely for its simplicity. The principles of plant symmetry that van Tieghem established are classic. Having defined the organs by their structure, he applied his method to several unanswered questions: the structure of the pistil (his paper on this subject received the Bordin Prize of the Académie des Sciences in 1867), the organization of the ovule, the orientation of the embryo, and the composition of the seed. In 1871 he was awarded a grand prize for his work on the root. Moreover, in his anatomical research on the root and the stem, van Tieghem distinguished between primary and secondary tissues. Starting in 1871, he showed how anatomy could reveal the affinities between plants. He compared organs of the same species in different areas, thus initiating the study of the effect of the environment on plants.

Van Tieghem also did research in plant physiology. His experiments on the effect of cold on seeds and on the resultant “extreme slowing down” of their life processes were crucial. Through his work on the potential of the various parts of the embryo contained in the seed, he proved that each of the embryo’s organs is autonomous and can grow without the others, whether or not the seed contains endosperm. He demonstrated that young embryos deprived of endosperm can be nourished by an artificial paste the chemical composition of which is close to that of specific endosperm.

After 1893 van Tieghem turned to work on parasites. He examined many exotic plants on which various degrees of degeneration of the ovule could be detected. His findings concerning this female organ led him to define the structure of the ovule and its integuments in a number of plants. Van Tieghem’s work revealed the need for new classification of the phanerogams, based on the ovule and the seed, as well as a complete classification based on the ovule of plants.

Numerous and varied as they are, all van Tieghem’s publications are characterized by an important new approach to botany; function is always studied in relation to structure and development.

In addition to conducting scientific investigations, van Tieghem held many offical posts. From 1873 to 1886 he was professor of biology at the ècole Centrale des Arts et Manufactures; from 1885 to 1912, professor at the École Normale Supérieure des Jeunes Filles at Sèvres; and from 1898 to 1914, professor of plant biology at the Institut Agronomique. Students still find his Traitè de botanique useful.

BIBLIOGRAPHY

I. Original Works. Many of van Tieghem’s writings are listed in Notice sur les travaux scientifiques de M. Ph. Van Tieghem (Paris, 1876). See also “Recherches sur la structure du pistile et sur l’anatomie comparé e de la fleur, avec un atlas de 16 planches,” in Mèmoires des savants ètrangers, 21 (1871), for which van Tieghem was awarded the Bordin Prize in 1867; “Recherches sur la symé trie de structure des plantes vasculaires,” in Annales des sciences naturelles, Botanique, 5th ser., 12 (1871); Traitè de botanique copnforme á l’ètat prèsent de la science, 3rd ed. (Paris, 1884); Elèments de botanique, I (Pairs 1886). II (Paris, 1888); and “Recherches comparatives sur l’origine des members endogènes dans les plantes vascularies,” in Annales des sciences naturelles 7th ser. 8 written with Henri Douliot.

II. Secondary Literature. Seee G. Bonnier, “L’oeuvre de Philippe Van Tiegham,” in Revue gènèrale de botanique, 26 (1914) 353-441; and J. Costantin, “Philippe Van Tieghem,” in Nature, REvue des sciences et de leurs applications aux arts et è l’industrie no. 2137 (1914), 394-396; and “Lerole de Brogniart, de Renault et de Van Tiedhem dans la Chaire d’organographie du Musé;’sum,” in ARchives du Musé um nationale d’historie naturelle, 6th ser., 12 (1935), 319-324.

A. NougarÈde