370 GENERAL ANATOMY. 



the others. The petrous portion of the temporal bone is of all 

 the parts that which contains most.* 



587. The bones are of a yellowish white colour and opaque, 

 but it is especially by their hardness, their little flexibility, and 

 their resistance to rupture that they are remarkable, and it is 

 by these properties that they perform their part in the organ- 

 ism. However little flexibility and compressibility they pos- 

 sess, they are elastic. 



They also possess a slow but real extensibility and power 

 of contraction. Thus the maxillar sinus, the nasal fossae, the 

 orbit, &c. are gradually enlarged by the development of tu- 

 mours in their interior. These cavities also return to their 

 previous state when they are freed of these causes of exten- 

 sion. The alveoli contract and become effaced after the loss 

 of the teeth, &c. 



They possess no other kind of contraction. Sensibility ex- 

 ists in them only in the morbid state. Their power of forma- 

 tion is very remarkable in these two respects, that all the phe- 

 nomena\vhich belong to it, as their first formation, separation, 

 alterations of texture, &c. take place in a very slow manner, 

 while the faculties of reproduction and accidental production 

 are greater in them than in any other tissue. 



588. The formation of the bones, ossification, or osteoge- 

 nesist is a phenomenon which has much occupied the attention 

 of observers, and which is, in fact, highly worthy of it. 



* John Davy, in Monro's Outlines of the Anatomy of the Human Body. 

 Edinb. 1813. 



-j- H. Eysson. de Ossibus infantis, cui tractatui annexus cst V. Colter, Os- 

 sium infantis historia, 12mo. Groning. 1659. Th. Kerkring-. Osteogenia 

 foetus. Lug-d. Bat. 1717. R. Nesbitt. The Human Osteogeny. Lond. 

 1736. J. Baster. De Osteogenia. Lug-d. Bat. 1731. A. Vater et Ulmann. 

 Osteogenia. Viteb. 1733. Albinus. Ann. Jicad. lib. vi. vii. Id. Icones Os- 

 sium Foetus Humani. accedit Osteogeniae brevis historia. Lugd. Bat. 1737. 

 Duhamel. Mem. de I'Jlcad. Roy. des Sc. 1739, 41, 43-46; Haller, Expe- 

 rimenta de Ossium formations in op. min. ii. Herissant, Mem. de tJLcad. 

 Roy. des 8c. 1768. C. Y. Senff. Nonnulla de. incremento ossium embryo- 

 nurn in primis graviditatis mensibus. Hals, 1801. J. Fr. Mcckel. Lent- 

 sckes JLrcliiv. fur die Physlolog. b. i. ii. 4. J. Howship. Expcr. and Observ. 



