28 PHYSIOLOGICAL SEftlES. 



A. 108. A longitudinal section of the tibia of a younger Hog, 

 with a thin exterior layer of coloured bone. 0. C. 201. 



By comparing this specimen with, and observing the size of the 

 medullary cavity in, the preceding, the extent of the absorbing 

 process will appear manifest ; since the cavity is rendered suffi- 

 ciently large to contain the entire bone of the earlier period of 

 growth. 



" In the formation of a bone, ossification begins in a spot, and 

 gradually increases. By feeding an animal on madder, it is shown, 

 that while bony matter is deposited on the outside of the bone, 

 the absorbents are removing it from the inner side, otherwise 

 the bone would become heavy and clumsy, and unfit for motion ; 

 therefore as the bony matter which was deposited becomes useless, 

 nature removes it by the absorbents." John Hunter, MS. Lectures. 

 See also " Experiments and Observations on the Growth of Bone, 

 from the Papers of the late Mr. Hunter, by Everard Home, Esq., 

 F.R.S.," in the Transactions of a Society for the Improvement of 

 Medical and Chirurgical Knowledge, vol. ii. p. 277. Read Oct. 4, 

 1798. 



The colouring-matter of madder has a great affinity to phosphate 

 of lime, which, if artificially precipitated from a solution coloured 

 with madder, carries down with it the colouring-matter in a state 

 of combination which water does not disturb. The colouring prin- 

 ciple of madder is very slightly soluble in water, but is abundantly 

 so in albuminous fluid ; and consequently is readily carried along 

 with the circulating blood dissolved in the serum, and is deposited, 

 combined with the phosphate of lime, wherever this salt is sepa- 

 rated from the blood to contribute to the increase of reparation of 

 bone. We may accordingly draw an inference as to the part of a 

 growing bone which receives the accessions of osseous substance 

 by observing the deposition of the madder-stained phosphate of 

 lime. 



llunterian. 



Formation of Bone, exemplified in the Growth of the 

 Antlers of Deer. 



All the examples are from the Fallow Deer (Cervus tlama). 



A. 109. A transverse section of part of the palm of the antler, 

 while in a growing state, injected. 0. C. 103. 



The parts which invest the antler at this period are, a vascular 

 membrane similar to periosteum and continued from the peri- 



