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).
From them are developed two distinct types of histological elements; the genital cells and the cnidoblasts or mothercells of the nematocysts.
Protohydra is a marine genus characterized by the absence of tentacles, by a great similarity to Hydra in histological structure, and by reproduction by transverse fission.
The use of the term to mean the individualized nucleated mass of living protoplasm, which, whether with or without a limiting membrane, primitively forms the proximate histological element of the body of every organism, dates from the second quarter of the i9th century.
IFor the histology of the comparatively simple but in many respects aberrant Bog-mosses (Sphagnaceae), see BRYOPHYTA.] The stems of the other mosses resemble one another in their main histological features.