152 APPENDIX. [No. III.A. 



the extreme circles round each Haversian canal with the corresponding 

 corpuscules of the neighbouring canal. Between the system of corpuscules 

 surrounding the Haversian canal there is no row taking the general 

 direction of the bone, as some have asserted. 



If the Haversian canals are examined in a recent subject, where the 

 capillaries are well filled with blood, they are observed to contain vascular 

 tubes, and the blood can be distinctly recognized in them. To ascertain 

 this fact it is better that the bone be scraped, and no heat applied to fix 

 the bone ito the glass. 



The corpuscules are arranged around the Haversian canals in a series 

 of rows proportionate to the size of the canals : thus a small canal has one, 

 two, or three rows round it, while a large canal has five or six rows. It is 

 to be noticed that the rows around the medullary canal and external edge 

 of the bone seldom exceed two or three series. 



An opinion is very prevalent amongst physiologists that these little 

 bodies are solid ; and many consider that they consist of the phosphate of 

 lime and earthy matter of bone ; but this opinion appears to be incorrect, 

 from viewing sections of bone under different circumstances. 



A similar opinion has been entertained of the fine lines running from 

 the corpuscules, which have been termed the calcigerous tubes, but I would 

 suggest the name of corpuscular lines or tubes, as the truth of this will be 

 shown presently. 



When a section of fresh bone is examined, these bodies appear opaque 

 as well as their lines ; but when a section from the same bone is thoroughly 

 boiled in balsam of Canada, the balsam enters the canals of Havers, the 

 corpuscular lines disappear, with few exceptions, and some of the corpuscules 

 become transparent and nearly invisible, and others partially transparent. 

 The same effect has been produced by our forefathers in their process of 

 embalming ; for in the tibia of a mummy which I possess, the corpuscules 

 are transparent, and most of them are decidedly filled with a yellow matter 

 similar to that which exists in the blood-vessels. The corpuscular lines 

 are so translucent as to be scarcely visible. In this case the canals of 

 Havers were also filled with yellow matter. 



When the section of recent bone is ground down to the utmost possible 

 limit, the corpuscules either appear as a transparent irregular oval ring, or 

 they have the appearance of containing some shrivelled matter in their 

 interior. In these cases the section of bone is only a portion of corpuscule 

 in thickness. 



The corpuscules with the lines are exceedingly opaque when a section 

 of bone is examined in which the canals of Havers are filled apparently 

 with adipocere, which occasionally happens after maceration. 



If a thin section of bone is thoroughly calcined, then soaked in oil, 

 and afterwards carefully ground down extremely thin, the canals of Havers, 

 the corpuscules, and corpuscular canals will be quite visible in the sub- 

 stance of the bone.* _^ 



* The labour and care required to make these specimens are very great. It 

 is better to calcine a thin section in a crucible, over a hot fire, then to place it in 

 oil, and keep it there for a very long period, when it may be fixed to the glass 

 with balsam of Canada. No heat should be applied, but it must be allowed to 

 remain till it spontaneously dries, when its thickness may be further reduced. and 

 gently polished. 



