Resumo Durante a segunda metade do século XVIII, o ensino do desenho na Espanha foi reforçado e sistematizado pela abertura de academias e escolas de desenho oficiais, onde se ensinava um método de trabalho completo, constituído por fases sucessivas para definir todos os elementos da composição pictórica. Francisco de Goya, o mais notável artista espanhol de seu tempo, usou o desenho de forma variada, experimentando e acomodando as técnicas a suas preferências e capacidades expressivas. Entretanto, Goya não era o único, visto que outros artistas trabalhavam nos mesmos âmbitos que ele. Dessa forma, colocam-se as seguintes questões: somente Goya teria experimentado e adaptado as técnicas de desenho? Teria o resto de seus contemporâneos praticado apenas o desenho acadêmico? Para responder a estas perguntas, o texto aborda as técnicas e formas de desenhar de outros artistas da época, em comparação com aquelas usadas por Goya. Nesse sentido, o artigo analisa os desenhos desses artistas e do pintor, conservados em coleções tanto espanholas como internacionais, levando em consideração a sua aprendizagem e o seu processo de trabalho, assim como as ideias da época, recolhidas em distintos documentos e estudos. O resultado revela que Goya não foi o único a experimentar, dado que os artistas usavam as distintas técnicas de desenho como mais lhes convinha, de acordo com seu método de trabalho, suas necessidades expressivas e suas preferências.

Abstract In Spain, drawing instruction was reinforced and systematized thanks to the opening of official academies and drawing schools during the second half of the eighteenth century. These academies and schools taught a comprehensive working method involving successive phases to define all of the elements of pictorial composition. The most significant Spanish artist of the time, Francisco de Goya, made varied use of drawing by experimenting and adapting techniques to his preferences and expressive capabilities. However, Goya was not alone, since other artists worked in the same fields as him. Was Goya the only artist to experiment and alter drawing techniques? Did the rest of his contemporaries merely adhere to the academic style? In order to answer these questions, the techniques and drawing styles of other artists during the period are analyzed and compared with those utilized by Goya. To accomplish this analysis, this paper studies Goya's and his contemporaries' extant drawings, which are kept in both Spanish and international collections. Through the study of these drawings, this paper seeks to take into account the artists' learning and working processes, as well as the ideas that prevailed at the time that are gathered in diverse documents and studies. The results reveal that Goya was not the only one to experiment, since artists used different drawing techniques based upon what suited them best according to their working method, artistic expressive needs, and preferences.

ABSTRACT: The application and development of environmental laws governing watershed management requires identification of biological indicators, parameters and measures to establish its ecological status, for which the present study aims to characterize the ecological indicator value of stream benthic algae in an urban area of Mexico City. Six sites of the Magdalena river were studied in the most contrasting seasons: dry-warm, rainy and dry-cold. At each site the physicochemical parameters of water were recorded and 10 samples were collected: Five with visible algal growths and five with diatoms. The environmental quality of each site was determined by the trophic status and its confirmation with the richness and benthic algal diversity, through a canonical correspondence analysis and the calculation of the indicator value of species (IndVal). According to the trophic status, three groups of sites were recognized. The first group (G1) was assessed as reference of the oligotrophic conditions and presented 11 species with the highest IndVal, protruding: Encyonema silesiacum, Gomphonema parvulum, Navicula cryptocephala, Planothidium lanceolatum, Vaucheria bursata, Placoma regulare and Nostocparmelioides. A second group (G2) was associated with 15 species considered detectors, which were tolerant to increased nutrients in at least one season, such as Diatoma mesodon and Prasiola mexicana. The third group (G3) included sites with species that had a wide range of tolerance to pollution: Fistulifera saprophila, Nitzschia minuta, Nitzschia palea, Nitzschia recta and Phormidium autumnale. The species IndVal of Magdalena River has established reference sites of good environmental quality and those that are altered by human activities, therefore they are recommended as the first step in a methodological proposal for a long-term biomonitoring through a biological index.

RESUMEN: La aplicación y desarrollo de las leyes ambientales que regulan el manejo de cuencas requiere la identificación de indicadores biológicos, los parámetros y las medidas para establecer su estado ecológico, para lo cual el presente estudio tiene como objetivo caracterizar el valor indicador ecológico de las algas bentónicas en una corriente urbana de la Ciudad de México. Se estudiaron seis sitios del río Magdalena en las estaciones más contrastantes del año: seca cálida, lluviosa y seca fría. En cada sitio se registraron los parámetros fisicoquímicos del agua y se recolectaron 10 muestras: cinco con crecimientos algales visibles y cinco con diatomeas. La calidad ambiental de cada sitio fue determinada por el estado trófico y su confirmación con la riqueza y diversidad algal bentónica, a través de un análisis de correspondencia canónica y del cálculo del valor indicador de las especies (IndVal). De acuerdo con el estado trófico se reconocieron tres grupos de sitios. El primer grupo (G1) fue valorado como de referencia de condiciones oligotróficas y presentó 11 especies con el mayor IndVal, sobresaliendo: Encyonema silesiacum, Gomphonema parvulum, Navícula cryptocephala, Planothidium lanceolatum, Vaucheria bursata, Placoma regulare y Nostoc parmelioides. Un segundo grupo (G2) se relacionó con 15 especies consideradas como detectoras, las cuales fueron tolerantes al incremento de nutrientes en al menos una época del año, tales como Diatoma mesodon y Prasiola mexicana. El tercer grupo (G3) incluyó sitios con especies que presentaron una amplia tolerancia a la contaminación: Fistulifera saprophila, Nitzschia minuta, Nitzschia palea, Nitzschia recta y Phormidium autumnale. El IndVal de las especies del río Magdalena ha permitido establecer los sitios de referencia de buena calidad ambiental y los que aparecen alterados por las actividades humanas, por lo que se recomiendan como el primer paso de una propuesta metodológica que permita el biomonitoreo a largo plazo a través de un índice biológico.