Emil Hassler (20 June 1864 – 4 November 1937) (French:, Spanish: ) was a Swiss physician, ethnographer, naturalist and botanist well known for his collections and contributions to the description of the flora and culture of Paraguay. Early life and education Born in Aarau, Switzerland in 1864, the son of Johann Friedrich Hassler and Marie Stampfli, Hassler was educated at the Ecole des arts et métiers d'Aarau from 1880 to 1882. He studied medicine in France, completing his studies in Rio de Janeiro, Brazil. Career In 1884 he began practising medicine in Cuiabá, Brazil. Between September 1885 and March 1887 he undertook his first voyage of exploration in the Matto Grosso of Brazil starting from Cuiabá, making his first ethnographic collections. In 1887 he moved to a hospital at San Bernardino near to Asunción in Paraguay. In 1889 he was curator for Paraguay in the World Exhibition in Paris. In 1893 Hassler presented his ethnographic work at the Chicago World Fair. He made his first botanical collections in 1895 and in 1896 considered returning to Switzerland settle permanently but, in 1897, decided, instead, to go to Paraguay for more botanical exploration. These led to the 1898 publication of the first part of Plantae Hasslerianae published in the academic journal, Bulletin de l'Herbier Boissier, with further parts published through to 1907. In June 1898 he moved to San Bernardino and built his first house in . Between 1898 and 1908 he undertook several botanical exploration trips nationwide, primarily in the Eastern region with collaborator Teodoro Rojas. He regularly returned to Switzerland during this period and, in 1909 he moved more permanently, settling in Pinchat near Geneva. He researched his collections, publishing numerous studies, some in conjunction with Robert Chodat who accompanied him on a further field trip to Paraguay in 1914. In 1919 Hassler deposited his personal herbarium collection in the Conservatory and Botanical Garden of the City of Geneva whose director, Dr John Briquet, was a personal friend. In 1920 he returned to Paraguay to definitively settle in San Bernardino. He built "Villa Mon Repos" as his second home but continued to travel regularly back to Switzerland. In 1921 he participated in the foundation of the Sociedad Científica del Paraguay (Scientific Society of Paraguay), of which he became honorary president. In 1932, during the Chaco War between Bolivia and Paraguay he established and ran a hospital for the wounded in