Lazzaro Spallanzani (1729-1799) e o torpedo: um tipo de peixe elétrico?

• Autor(a) principal: Jensen, Gerda Maisa
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da PUC_SP
• Texto Completo: https://tede2.pucsp.br/handle/handle/13411
• topic: Lazzaro Spallanzani; Peixe elétrico; Torpedo; Entorpecimento; Eletricidade animal; Spallanzani, Lazzaro -- 1729-1799; Eletrofisiologia -- Obras anteriores a 1800; Historia natural -- Obras anteriores a 1800; Orgaos eletricos em peixe; Electric fish; Torpedo; Animal electricity; Numbness; CNPQ::CIENCIAS HUMANAS::HISTORIA::HISTORIA DAS CIENCIAS

The Italian naturalist Lazzaro Spallanzani (1729-1799) took up the study of several issues of Natural History amongst which, the numbness phenomenon caused by fish called torpedoes in their preys or in human beings. Well known since the Ancient times once a fable, it became subsequently the object of inquiry of the natural philosophers from XVII and XVIII centuries. They witnessed the veracity of the phenomenon and described the morphology and the anatomic of these fish, trying to explain it origin and cause of the numbness. In this Dissertation, we present some of the inquiries on the subject conducted by Spallanzani, to ascertain whether they were based on the knowledge available in the period and if his observations and experiments were well planned and executed. To do so, we present some of the explanations for the phenomenon, ranging from mechanical and electrical hypotheses, for some predecessors and contemporaries of Spallanzani. Then, in order to contextualize the study in the general scope of the investigations of Spallanzani, details of his training and academic activities are given, with emphasis on his naturalistics travels and maintenance of museums of Natural History. Finally, the process of investigation that he conducted on the torpedoes, between the years 1780 and 1782 is detailed. The report of his observations and experiences as well as the results were summarized by Spallanzani in a letter dated February 23 of 1783, addressed to the Marchis Girolamo Lucchesini and published in the same year, in two journals aimed at disseminating scientific Italians, the Opuscoli scelti sulle Scienze e sulle Arti and the Giornale de Letterati. We compared this letter with to excerpts of the diaries, published only recently, about his naturalistic journeys that provided Spallanzani access and opportunity to conduct their studies on the torpedoes. Our analysis led us to conclude that Spallanzani took into account the past and contemporary studies on the phenomenon, his guided through their research hypotheses (mechanical and electrical) that subsidized these studies. Spallanzani concluded that although the shock caused by the fish does not produce sparks or express phenomena of attraction and repulsion (as occurred with static electricity studied at the time), the numbness caused by torpedoes in their preys, in the hands of fishermen and scholars was an electrical phenomenon of the same nature as manifest in the atmosphere or the bottle of Leyden