STRUCTURE OF OSSEOUS TISSUE. 125 



isolated, which forms the wall of the cavities representing the 

 form of the so-called bone corpuscles and their processes. The 

 observations of Kolliker* and of Neumanrrj- have an important 

 bearing on this explanation, since in a similar series of experi- 

 ments they frequently obtained isolated tubules, simulating the 

 form of the Haversian canals. The question, what is the nature 

 of the contents of these cavities during life ? is, as thus broadly 

 stated, not easy to answer. 



According to a very recent communication, KlebsJ has con- 

 vinced himself that their contents in the older bones, even when 

 quite fresh, is of a gaseous nature. He rests his assertion espe- 

 cially upon the dark appearance the bone corpuscles present by 

 transmitted light, either in bones examined in the fresh state or 

 under water ; secondly, because by means of an air pump a large 

 quantity of gas can be obtained from the bones ; and lastly, 

 because exposure to a solution of potash, which effects the 

 absorption of the contained air (CO 2 ), renders the corpuscles 

 transparent. 



The bone corpuscles appear to be destitute of air in those 

 bones only which are in contact with soft parts, or in foetal 

 bones; in point of fact, it is not difficult to demonstrate 

 in many instances, that cell-like structures containing nuclei 

 occupy the lacunse of bone. 



For observations of this nature the large lacunae of em- 

 bryonic bones are well adapted, as are also those which are 

 found in the younger layers of bone that lie immediately sub- 

 jacent to the periosteal connective tissue investing the bones. 

 Good results may be obtained from bones decalcified with weak 

 acids (chromic acid, or a mixture of this with a little hydro- 

 chloric acid), especially if thin sections are tinted with car- 

 mine. On the other hand, it is difficult, even after this 

 procedure, in the case of old bones, to recognise with certainty 



* Mikroskopische Anatomie, p. 83. 



f Loc. cit. 



J Centralblatt fur die medicinische Wissenschaften, 1868, p. 61. 



Bonders, Mulder, Versuch einer physiologische Chemie, p. 595. Kolli- 

 ker, Mikroskopische Anatomie, Band ii., p. 297. Rouget, Journal de la 

 Physiologic, 1858, p. 764. Beale, loc. cit., p. 128. 



M2 



