OSSEOUS TISSUE. 



853 



lation, even though the contents of the cells 

 remain unaltered, which is not probable. 



Cells of smaller form and having branching 

 tubes are to be found in the vegetable world. 

 The shells of various fruits, as the cocoa-nut, 

 peach, common nut, &c. present cells so like 

 those of bone that a section of shell has often 

 been mistaken for one of bone. In this instance 

 they also answer the purposes of circulation. 



The growth of bones. Many experiments 

 have been made to ascertain the mode of 

 growth in bones, but they have given as their 

 results the direction of increase rather than the 

 process of interstitial growth. The experiments 

 alluded to are commonly spoken of as the 

 madder experiments, and were instituted by 

 Du Hamel, Detlif, Hunter, Stanley, Paget, 

 and others. 



It was discovered that phosphate of lime 

 acts upon the colouring matter of madder as a 

 mordant. Thus, if phosphate of lime be pre- 

 cipitated from a state of chemical combination 

 in a solution of madder, the colouring matter 

 of the madder is carried down with the phos- 

 phate in a state of chemical combination, im- 

 parting to the phosphate a red colour, which is 

 not diminished by repeated washing, but gra- 

 dually fades by exposure to light. But, before 

 this discovery was made, it was found that the 

 bones of some pigs that had been accidentally 

 fed upon madder were rendered red. Atten- 

 tion having been drawn to this curious fact that 

 madder given in the food reddens the bones 

 of the animal, the madder experiments were 

 undertaken, and led to the following results. 



If madder be given to a growing animal, 

 and the bones be examined by making a sec- 

 tion of a cylindrical bone, a ring of reddened 

 bone will be seen to form the circumference of 

 the bone, and a similar reddened ring to form 

 the pahetes of the medullary cavity. If in this 

 experiment the animal had been old, these 

 rings of red would not have been seen, or, if 

 seen, only very faintly. From these two ex- 

 periments it has been deduced that the bone, 

 or rather the phosphate of lime, which has 

 been deposited during the exhibition of the 

 madder, has alone been reddened. 



If, however, after giving madder to a grow- 

 ing animal for a time, its use be discontinued 

 for a while and then be again given, several 

 rings of reddened bone will be observed on 

 making a section of a cylindrical bone, that is, 

 reddened bone will be deposited during the use 

 of the madder, and white bone at the interval 

 of its discontinuance. So that, by the alter- 

 nate use and disuse of madder, rings of red 

 and of white bone will be formed to a consi- 

 derable number. From these experiments it 

 has been deduced that bones increase in their 

 diameter by the development of the bone on 

 the surface somewhat in the same manner that 

 a crystal increases in size by additions to its 

 surface. 



Mr. Gibson, however, for a while threw some 

 doubts on the value of the madder experiments 

 and the deductions from them, by stating that 

 the serum of the blood had an affinity for the 



colouring matter of madder superior to that of 

 the phosphate of lime, and that the bone became 

 stained only after the serum had been tho- 

 roughly saturated with madder, and more, that 

 the serum, from the discontinuance of madder 

 in the food, or losing the colouring matter, 

 absorbed that existing in the bones. 



Mr. Paget has, however, proved that the 

 affinity is far stronger between phosphate of 

 lime and the colouring matter of madder than 

 between serum and the latter. These experi- 

 ments seem at first sight far more valuable than 

 a closer investigation will prove them to be, as 

 will be seen on considering the following fact, 

 namely, that not only is the surface of the bone 

 with the walls of the medullary cavity tinged red 

 by the exhibition of madder, but also the cir- 

 cumference of every Haversian canal through- 

 out the bone, in fact every surface that lies in 

 contact with a vessel or vessels. The fact that 

 every Haversian canal has its coloured ring had 

 escaped observation, as these experimenters 

 had been limited to the use of the naked eye, 

 whereas the Haversian canals, with their co- 

 loured rings, are only seen by the use of the 

 microscope. 



It therefore remains for observation to be 

 made upon the effects of consecutive feeding 

 with and without madder, upon the Haversian 

 canals, before any very accurate deductions 

 can be made. 



Other experiments have been tried in inves- 

 tigating the growth of bones. 



Rings of metal have been lightly fixed round 

 a long bone, which after a while has been found 

 to contain the rings in its medullary cavity, 

 from which it has been inferred that the bone 

 has grown by additions to its circumference, 

 while the medullary cavity has been enlarged by 

 the absorption of the bone forming its parietes. 

 These experiments, which were made by Du 

 Hamel, have been confirmed by Hunter and 

 Stanley. 



Experiments of a similar nature have been 

 made to determine the manner of growth in 

 the length of bones. Thus holes have been 

 bored in the tibia of a dog at definite intervals, 

 which intervals, after the lapse of some days, 

 have been found altered in the relative lengths. 

 The intervals near the ends of the bone have in- 

 creased considerably, while those situated near 

 the centre of the bone have scarcely changed. 

 Mr. Stanley has shown that in some animals 

 the growth is greatest at the distal end, while in 

 other animals it is greater toward the proximal 

 end of a long bone. 



In the two experiments which I have related 

 in a previous part of this article the walls of the 

 medullary cavity were as distinctly reddened as 

 the circumference of the bone, and the cir- 

 cumference of each Haversian canal as either. 

 These would therefore prove too much for the 

 theory which supposes that a long bone in- 

 creases its diameter by the depositions upon its 

 surface and under its medullary cavity by the 

 absorption of the walls. Supposing the idea 

 that phosphate of lime, which is deposited 

 during the exhibition of madder, is alone red- 



