916 
MR. A. FRASER ON THE DEVELOPMENT OF THE 
Summary and Besults. 
Summarizing this work the following conclusions can with safety he drawn. 
First. That the malleus is the proximal extremity of the mandibular cartilage, 
and that its manubrium is the last part to be developed. 
Second. That the incus is the proximal extremity of the hyoidean cartilage. That 
this is determined not only by continuity of embryonic cartilage (which is not always 
present) and its morphological and histological agreement with the remainder of the 
cartilage, but also by the relation which the chorda tympani nerve (mandibular branch 
of the seventh) bears to its long crus. That its orbicular apophysis is the last to 
develope ; its pedicular form of attachment appearing after birth. 
Third. That the stapes is developed as a circular ring of cells round the artery 
which has been described. That its connexion with the hyoidean cartilage is at first 
more close than with the periotic capsule; that of its individual parts the head and 
margins of the base are the last to appear, and that the fluted condition of the head, 
crura, and base is developed after birth. 
In conclusion, I have to express my warmest acknowledgments to my former teacher, 
Dr. Allen Thomson, but for whom this paper could not possibly have been in its 
present form. I am also much indebted to Professor Parker for information concern¬ 
ing the form and modifications of the two cartilages in the lower Vertebrates. 
Deferences. 
1. Meckel. Handbuch der Menschlichen Anatomie. Halle: 1820. 
2. Bathke. Ueber den Kiemenapparat, S. 122. Valentin. Handbuch der 
Entwickelungsgeschichte. Berlin : 1835. 
3. Huschke. Beitrage zur Physiologie und Naturgeschichte. Weimar: 1824, and 
Isis: 1822, S. 47, S. 890, and 1833, S. 678. 
4. BurdAch. Die Physiologie, II. S. 456, 465, Leipzig : 1828. 
5. Beichert. Ueber die Visceralbogen. Muller’s Archiv, 1837, S. 178. 
6. Gunther. Beobachtungen iiber die Entwickelung des Gehororgans bei Men- 
schen und hoheren Saugethieren. Leipzig : 1842. 
7. Magitot et Bobin. Memoires sur un organe transitoire de la vie foetale designe 
sous le nom de cartilage de Meckel. Annales des Sciences Naturelles, IV e serie, 
tome xviii., page 213. 
8. Bruch. Beitrage, &c., S. 18, 19, 158; and also Untersuchungen liber die 
Entwickelung der Gewebe bei den warmbliitigen Thieren. Frankfurt-a-M. : 
1863, 1867, S. 95, 99, 120. 
9. Huxley. Lectures on the Elements of Comparative Anatomy, 1864.—On the 
Bepresentatives of the Malleus and Incus of the Mammalia in the other Vertebrata. 
