In this article we examine the book "El estudio de la naturaleza en la escuela" by the Danish pedagogue Vilhelm Rasmussen (1869-1939), published by Editorial Labor in Barcelona in 1933, and its influence on the pedagogical standpoint of Margarita Comas Camps (1892-1972). Comas, who translated the book into Spanish, was a member of the group of educators of trainee teachers that spearheaded the project for the renewal of science teaching during the Second Spanish Republic (1931-1939). In line with the pedagogical principles and ideas of the New School and Nature Study movements, Rasmussen -- science writer, social democratic politician, atheist and Darwinist -- proposed replacement of the textbook and the memorisation of concepts in natural science classes, by observation, dialogue and drawing, as well as studies of the relationships between living things in their natural environment through outdoor excursions and the use of aquaria and terraria in the classroom. We analyse Comas's Spanish translation of "Nature study in the school" published in England in 1929 from the Danish original of 1909, as well as Rasmussen's pedagogical proposals that Comas included in "Contribución a la metodología de las ciencias naturales" (1937), the last of her books to be published prior to her exile in England. In Rasmussen, an author from a country geographically and culturally distant from Spain, Comas found an outstanding reference for the teaching of natural sciences.