Medical science further owes to him the classification of new growths on a natural histological basis, the elucidation of leucaemia, glioma and lardaceous tumours, and detailed investigations into many diseases - tuberculosis, pyaemia, diphtheria, leprosy, typhus, &c. Among the books he published on pathological and medical subjects may be mentioned Vorlesungen fiber Pathologic, the first volume of which was the Cellular-pathologic (1858), and the remaining three Die Krankhaften Geschwiilste (1863-67); Handbuch der speziellen Pathologic and Therapie (3 vols., 1854-62), in collaboration with other German surgeons; Gesammelte Abhandlungen zur wissenschaftlichen Medizin (1856); Vier Reden fiber Leben and Kranksein (1862); Untersuchungen fiber die Entwicklung des Schlidelgrundes (1857); Lehre von den Trichinen (1865); Ueber den Hunger-typhus (1868); and Gesammelte Abhandlungen aus dem Gebiete der afentlichen Medizin and der Seuchenlehre (1879).
In collaboration with Edward C. Potter he modelled the "Washington," presented to France by the Daughters of the American Revolution; the "General Grant" in Fairmount Park, Philadelphia, and the "General Joseph Hooker" in Boston.
Leo; on the other hand, Thomas of Celano's two Lives are free from the "tendencies" ascribed to them by Sabatier, and that of 1248 was written with the collaboration of Leo and the other companions; thus the best sources of information are those portions of the Speculum that can with certainty be carried back to Br.
A zarzuela, entitled Guerta a muerte, for which Emilio Arrieta composed the music, belongs to 1855, and to the same collaboration is due El Agente de Matrimonios.
His career as a dramatist very probably began by collaboration with other authors.