No. III.A.] APPENDIX. 153 



When the earthy matter is removed from calcined bone, the corpus- 

 cular lines disappear, but the corpuscules themselves, though transparent, 

 are still visible. 



In these instances the examination has been made by transmitted 

 light ; but differences, according to circumstances, are seen when the object 

 is viewed by light thrown on the surface. The corpuscules with the lines 

 appear white when a thin section is examined with a dark ground under- 

 neath it ; but a thick polished piece of bone, or a section of bone with a 

 portion of white paper underneath it, does not present these appearances. 

 The reflection of light from the deeper corpuscules is the reason why the 

 corpuscules are not apparent in a thick section, nor when white paper is 

 placed underneath one of greater tenuity. Those corpuscules which present 

 a transparent ring by transmitted light still appear white when viewed by 

 reflected light, for some are seen as white rings on a black ground, and 

 others as rings having a little irregular white matter in the centre. The 

 whiteness of the corpuscules is owing to the reflection of light from 

 the surface of the corpuscules, whilst between them it passes to the 

 back, and is absorbed. The same effect is produced when a piece of 

 black cloth or scratched glass is viewed under similar circumstances, in 

 which cases the elevations on the one and the depressions in the other 

 appear white. 



If, however, the piece of mummy-bone before mentioned be examined 

 by reflected light, the transparency of the corpuscules allows the light, in 

 some degree, to pass, and that part which is reflected appears of the same 

 yellow colour as when the section is viewed by transmitted light. 



Such are the principal circumstances which modify the appearances of 

 the corpuscules, and which may be thus summed up : first, that the earthy 

 matter is associated with the animal matter, and pervades every part of 

 the bone, which is shown in the section of burnt bone; secondly, that the 

 corpuscules may exist without any earthy matter being there, as in the 

 cartilage of the shark, or the animal matter of bone which is left after 

 maceration; thirdly, that the corpuscular canals communicate with the 

 Haversian canal, as the specimens boiled in Canada balsam prove ; fourthly, 

 that the corpuscules present themselves under two circumstances, for they 

 are either opaque, as in recent and adipocere bone, or transparent, as in 

 those boiled in balsam of Canada, as are also those of the mummy-bones. 



All these facts show that the corpuscules and corpuscular lines are 

 themselves cavities into which the various substances enter. We have 

 already mentioned that, in the bones of mummies, a yellow matter is found 

 in the corpuscules similar in appearance to that filling up the Haversian 

 canals. That they are cavities is farther proved by the corpuscules 

 appearing as rings when the section is reduced to extreme tenuity. 



Attempts were made to fill the cavities with a coloured substance by 

 various methods, such as had been effected in the bones of the mummy, 

 but watery solutions penetrated only for a short distance into the Haversian 

 canals, so that double decomposition of f errocyanate of potass and sulphate 

 of iron were found to be useless. 



Balsam of Canada and dragon's blood were melted together, . and 

 pieces of bone were then boiled in the mixture. On the examination of 

 thin sections of this, the Haversian canals were found filled with the com- 

 pound, but whether it entered farther I could not so satisfactorily make 



