Becquerel, Paul

(b. Paris, France, 14 April 1879; d. Évian, France, 22 June 1955)

biology.

Through his researches Paul Becquerel did much to explain the physiological nature of the plant seed and the reactions of protoplasm to freezing and dehydration. Becquerel, grandson of Edmond Becquerel and nephew of Henri Becquerel, received his licentiate in natural sciences at the Faculty of Sciences at Paris in 1903 and his doctorate in 1907. In that same year he was named an assistant at the Faculty of Sciences. For a period of time after World War I, Becquerel was a member of the Faculty of Sciences at Nancy, following which, in 1927, he was appointed professor of general botany at the University of Poitiers. He remained at Poitiers until his retirement.

Becquerel began his career with researches on the nature of the life of seeds. Were they, as some physiologists from Spallanzani through Claude Bernard had suggested, actually nonliving, in a state of suspended or latent life? Or were they merely in a state in which the life processes were greatly slowed?—an idea suggested by, among others, Leeuwenhoek and Gaston Bonnier, one of Becquerel’s teachers in Paris. After studying the structure and function of the various parts of seeds, Becquerel concluded that a portion of the seed always lived, protected from hostile external environments by an impermeable protective layer. Shorn of this layer, seeds could easily be killed by toxic liquids and gases. However, Becquerel went on to show that plant and animal tissue could in fact attain a state of suspended or latent life. He produced this condition in seeds; in fern, moss, bacteria, and mushroom spores; and in algae, rotifers, and infusoria by dehydrating them as much as possible in a vacuum. Living objects so treated could withstand exposure to liquid hydrogen (ca. —253°C.) and liquid helium (ca. —269°C.) and still be revived by warming and rehydration.

Becquerel then turned his attention to naturally occurring cases of “suspended life.” Working with seeds of known ages—from 25 to 135 years old—he was able to produce a small percentage of germinations; and, in later experiments (1933), he was able to bring about the germination of two 158-year-old seeds of Cassia multijuga. He found in these results confirmation of his ideas, maintaining that these seeds had retained their germinative ability because they had undergone a strong dehydration and their seed coats were quite thick.

In 1937 Becquerel began a study of the effects of freezing on vegetable protoplasm, showing in 1939 that plant cells are not killed by plasmolysis upon freezing; rather, the lowered temperature induces synaeresis. This was elaborated upon in a 1949 paper.

BIBLIOGRAPHY

Becquerel’s work appeared in a large number of short papers, most of them published in the Comptes rendus de I’Académie des sciences, Paris. Among his most important papers were the following: “Action de I’air liquide sur les graines décortiquées,” in Comptes rendus de I’Académie des sciences, Paris, 140 (1905). 1652–1654: “Recherches expérimentales sur la vie latente des spores des Mucorinées et des Ascomycétes aux basses températures de I’hydrogène liquide,” ibid., 150 (1910), 1437–1439; “Action abiotique des rayons ultraviolets sur les spores sèches aux basses températures et l’origine cosmique de la vie,” ibid., 151 (1910), 86–88; “La suspension de la vie des graines dans le vide à —271°C.,” ibid., 181 (1925), 805–807; “La vie latente des graines de pollen dans le vide à 271°C. au-dessous de zéro,” ibid., 188 (1929), 1308–1310; “La vie latente des spores des Fougèares dans le vide aux basses températures de I’hélium liquide,” ibid., 190 (1930), 1134–1136: “La vie latente des spores des bactéries et des moisissures,” in Travaux cryptogamiques, dédieés à Louis Mangin (Paris, 1931), pp. 303–307; “La vie latente des spores des Mousses aux basses températures,” in Comptes rendus de I’Académie des sciences, Paris, 194 (1932), 1378–1380; “L’anhydrobiose des tubercules des Renoncules dans l’azote liquide,” ibid., 194 (1932), 1974–1976; “La reviviscence des plantules desséchées soumises aux actions du vide et des très basses températures,” ibid., 2158–2159; “Sur la résistance de certains organismes végétaux aux actions des basses tempeératures de l’azote et de l’hélium liquides, reéalisées au laboratoire cryogène de Leiden,” in Actes du Vlème Congrès International du Froid (1932), IV, 23–27: “Role de la synérèse dans le mécanisme de la congélation cellulaire,” in Chronica botanica, 5 (1939), 10–11, a brief summary article:“Reviviscence du Xanthoria parietina desséché avec sa faune, six ans dans le vide et deux semaines à — 189°C. Ses conséquences biologiques,” in Comptes rendus de l’Acadeémie des sciences, Paris, 226 (1948), 1413–1415; and “L’action du froid sur la cellule végétale,” in Botaniste, 34 (1949), 57–74.

A short biographical obituary of Becquerel, without bibliographical material, appeared in Comptes rendus de l’Académie des sciences, Paris, 241 (1955), 137–140.

Alan S. Kay