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   PRINGSHEIM, NATHANAEL (1823–1894), German botanist, was born at Wziesko in Silesia, on the 30th 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 (1860), Hydrodictyon (1861), and Pandorina (1869); the last-mentioned memoir bore the title Beobachtungen über 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 authors point of view is that of Naegeli (1817–1891) 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 1874 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 Jahrbücher für 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.

 PRINSEP, JAMES (1799–1840), Anglo-Indian scholar and antiquary, was born on the 20th of August 1799. In 1819 he was given an appointment in the Calcutta mint, where he ultimately became assay-master, succeeding H. H. Wilson, whom he likewise succeeded as secretary of the Asiatic Society. Apart from architectural work (chiefly at Benares), his leisure was devoted to Indian inscriptions and numismatics, and he is remembered as the first to decipher and translate the rock edicts of Asoka. Returning to England in 1838 in broken health, he died in London on the 22nd of April 1840. Prinsep’s Ghat, an archway on the banks of the Hugli, was erected to his memory by the citizens of Calcutta.  PRINSEP, VALENTINE CAMERON (1838–1904), English artist, was born on the 4th of February 1838. His father, Henry

Thoby Prinsep, who was for sixteen years a member of the Council of India, had settled at Little Holland House, which became a centre of artistic society. Henry Prinsep was an intimate friend of G. F. Watts, under whom his son first studied. Val Prinsep also worked in Paris in the atelier Gleyre; and “Taffy” in his friend Maurier’s novel Trilby, is said to have been sketched from him. He was an intimate friend of Millais and of Burne-Jones, with whom he travelled in Italy. He had a share with Rossetti and others in the decoration of the hall of the Oxford Union. He first exhibited at the Royal Academy in 1862 with his “Bianca Capella,” his first picture, which attracted marked notice, being a portrait (1866) of General Gordon in Chinese costume; the best of his later exhibits were “À Versailles,” “The Emperor Theophilus chooses his Wife,” “The Broken Idol and “The Goose Girl.” He was elected A.R.A. in 1879 and R.A. in 1894. In 1877 he went to India and painted a huge picture of the Delhi durbar, exhibited in 1880, and afterwards hung at Buckingham Palace. He married in 1884 Florence, daughter of the well-known collector, Frederick Leyland. Prinsep wrote two plays, Cousin Dick and Monsieur le Duc, produced at the Court and the St James’s theatres respectively; two novels; and Imperial India: an Artist’s Journal (1879). He was an enthusiastic volunteer, and one of the founders of the Artists' Corps. He died on the 11th of November 1904.  PRINT, the colloquial abbreviation used to describe printed cloths generally, though it is most commonly applied to the staple kinds of cotton goods. The word must be distinguished from “printer,” which refers to the regular kinds of cotton cloths intended for printing. (See .)  PRINTING (from Lat. imprimere, O. Fr. empreindre), the art or practice of transferring by pressure, letters, characters or designs upon paper or other impressible surfaces, usually by means of ink or oily pigment. As thus defined, it includes three entirely different processes: copperplate printing, lithographic or chemical stone-printing, and letterpress printing. The difference between the three lies in the nature or conformation of the surface which is covered with the pigment and afterwards gives a reproduction in reverse on the material impressed. For the nature and method of preparing these surfaces see respectively (and allied articles),  and. In copperplate printing the whole of the plate is first inked, the flat surface is then cleaned, leaving ink in the incisions or trenches cut by the engraver, so that, when dampened paper is laid over the plate and pressure is brought to bear, the paper sinks into the incisions and takes up the ink, which makes an impression in line or lines on the paper. In lithographic printing the surface of the stone, which is practically level, is protected by dampening against taking the ink except where the design requires. In letterpress printing the printing surface is in relief, and alone receives the ink, the remainder being protected by its lower level. Before the invention of typography, pages of books, or anything of a broadside nature, were printed from woodcuts, i.e. blocks cut with a knife on wood plankwise, as distinct from wood engravings which are cut with a burin on the end grain, a more modern innovation. These woodcuts, like the lithographic or engraved surface, served one definite purpose only, but in typography the types can be distributed and used again in other combinations. The term “printing” is often used to include all the various processes that go to make the finished product; but in this article it is properly confined to “press-work,” i.e. to the work of the printing-press, by which the book, newspaper, or other printed article, when set up in type and ready as a surface to be actually impressed on the paper, is finally converted into the shape in which it is to be issued or published.

Before dealing with modern machinery it will be necessary to consider the historical evolution of the printing-press, especially since the middle of the 19th century, from which point printing machinery has developed in a most remarkable manner.