NATHANAEL

See also:

• NATHANAEL PRINGSHEIM (1823-1894)

PRINGSHEIM (1823-1894)  , German botanist, was born at Wziesko in Silesia, on the 3oth of November 1823 . He studied at the universities of Breslau, Leipzig, and Berlin successively . He graduated in 1848 as doctor of philosophy with the thesis De forma et incremento stratorum crassiorum in plantarum cellula, and rapidly became a leader in the great botanical renaissance of the 19th century . His contributions to scientific algology were of striking interest . Pringsheim was among the very first to demonstrate the occurrence of a sexual process in this class of plants, and he drew from his observations weighty conclusions as to the nature of sexuality . Together with the French investigators G . Thuret and E . Bornet, Pringsheim ranks as the founder of our scientific knowledge of the algae . Among his researches in this field may be mentioned those on Vaucheria (1855), the Oedogoniaceae (1855-1858), the Coleochaeteae (186o), Hydrodictyon (1861), and Pandorina (1869); the last-mentioned memoir bore the title Beobachlungen fiber die Paarung de Zoosporen . This was a discovery of fundamental importance; the conjugation of zoospores was regarded by Pringsheim, with good reason, as the primitive form of sexual reproduction . A work on the course of morphological differentiation in the Sphacelariaceae (1873), a family of marine algae, is of great interest, inasmuch as it treats of evolutionary questions; the author's point of view is that of Naegeli rather than Darwin . Closely connected with Pringsheim's algological work was his long-continued investigation of the Saprolegniaceae, a family of algoid fungi, some of which have become notorious as the causes of disease in fish .

Among his contributions to our knowledge of the higher plants, his exhaustive monograph on the curious genus of

water-ferns, Savinia, deserves special mention . His career as a morphologist culminated in 1876 with the publication of a memoir on the alternation of generations in thallophytes and mosses . From 1894 to the close of his life Pringsheim's activity was chiefly directed to physiological questions: he published, in a long series of memoirs, a theory of the carbon-assimilation of green plants, the central point of which is the conception of the chlorophyll-pigment as a screen, with the main function of protecting the protoplasm from light-rays which would neutralize its assimilative activity by stimulating too active respiration . This view has not been accepted as offering an adequate explanation of the phenomena . Pringsheim founded in 1858, and edited till his death, the classical Jahrbuch fur wissenschaftliche Botanik, which still bears his name . He was also founder, in 1882, and first president, of the German Botanical Society . His work was for the most part carried on in his private laboratory in Berlin; he only held a teaching post of importance for four years, 1864-1868, when he was professor at Jena . In early life he was a keen politician on the Liberal side . He died in Berlin on the 6th of October 1894 . A fuller account of Pringsheim's career will be found in Nature, (r 895) vol. li., and in the Berichte der deutschen botanischen Gesellschaft, 1895) vol. xiii . The latter is by his friend and colleague, Ferdinand ohn . (D .

H .