In 1840 the Society numbered 700 members, and in 1841 the number rose to 1,000. The members then agreed to pay double the former subscription--_i.e._, twenty francs. The grounds had now increased to the extent of three and a quarter acres. In 1843 M. Westerman, at the request of the Council of Administration, was put at the head of the Society, and accepted the entire control of it, which, in spite of his age, he continued to hold until his death. In May, 1850, the Gardens occupied nearly five acres, and in the same year the Council instituted attractive concerts twice a week. In April, 1852, His Majesty the King paid a visit to the Gardens, with which he was much pleased. He presented them with his portrait, and gave the Society the name of ‘The Royal Zoological Society.’ In 1877 the last enlargement of the premises was completed. The Society, after many futile efforts, succeeded in obtaining from the Municipal Council a piece of land, on condition that the Society should erect on the site a large building, to be utilized as an aquarium, and that superior instruction in Zoology should be given to the University of the town, partly at the Society’s expense. In all, the extent of the Gardens was increased to more than twenty-five acres, for which 463,369 francs were paid. In 1888, the year in which the Society held its fiftieth anniversary, there were in the Gardens 378 animals of 141 different kinds, 2,009 birds of 462 different kinds, and 77 reptiles of 28 kinds. The aquarium, opened in 1882, consists of a large and small hall, in which are three big reservoirs containing sea water and fresh, pumped in by machinery after having been well filtered. In the large hall will be found sea-water tanks, the two fresh-water tanks being in the small hall. There is a very rich collection of fish in them from all parts of the world, and many others have been bred there. Besides contributing to the enjoyment of the public, this aquarium is greatly used for research work and the study of anatomy. Here Dr. Kerbert discovered the hitherto unknown fish parasite, _Chromatophagus parasiticus_. This aquarium is justly considered one of the most important institutions of its kind in Europe. For the study of ethnography a large museum has been built, in which is housed a fine collection of objects appertaining to that subject. Another spacious room was built during recent years for the rich collection of skeletons which the Society possessed, containing the celebrated collections of G. and E. Vrolik and the skeletons of animals which have died in the Gardens. The total number of skulls and skeletons reaches 1,500, and they are exhibited on long shelves.