who?
From top to bottom, Santiago Ramón y Cajal in the laboratories of the JAE c.1920, José Castillejo c.1920, and Blas Cabrera, director of the National Institute of Physics and Chemistry, in his laboratory, 1932.
“... Prepare them to be, in the future, scientists, writers, lawyers, doctors, engineers, industrialists ... but above all, men, people capable of conceiving an ideal ...”.

Manuel Bartolomé Cossío, Principios pedagógicos
de la Institución Libre de Enseñanza, 1908

Francisco Giner de los Ríos and Manuel Bartolomé Cossio were the intellectual fathers of the Junta para Ampliación de Estudios, while Santiago Ramón y Cajal, José Castillejo, Ramón Menéndez Pidal, Blas Cabrera, and Ignacio Bolívar were responsible for its implementation and further development.

Cajal, already a Nobel laureate, became president of this institution which included prominent figures of the arts and sciences. José Castillejo, professor of Roman law, was secretary. His skillfulness and intelligence were decisive for the success of the ambitious project designed by the JAE.

The linguist and philologist Ramón Menéndez Pidal and the physicist Blas Cabrera headed the two key sections of the JAE: the Center for Historical Studies and the National Institute of Science. These research institutions, founded in 1910, established a network of centers to promote research in all fields and to foster educational reform.  

When Cajal died in 1934, Ignacio Bolívar became president. He had been director of the Museum of Natural Sciences since 1901, an institution which he modernized and where he promoted research into geology, botany and zoology.