 Complete the following phrase:  Over the summer of 1868, his father took him to graveyards to find human remains for anatomical study. Early sketches of bones moved him to pursue medical studies. Ramón y Cajal attended the medical school of the University of Zaragoza, where his father worked as an anatomy teacher. He graduated in 1873, aged 21, and then served as a medical officer in the Spanish Army. He took part in an 