OSSIFICATION. .343 



who gives the following account of the circum- 

 stances that led him to notice it.* Happening to 

 be dining with a calico printer on a leg of fresh 

 pork, he was surprised to observe that the bones, 

 instead of being white as usual, were of a deep red 

 colour; and on enquiring into the circumstances, 

 he learned that the pig had been fed upon the 

 refuse of the dyeing-vats, which contained a large 

 quantity of the colouring substance of madder. So 

 curious an effect naturally attracted the attention 

 of physiologists ; and many experiments were un- 

 dertaken with a view to ascertain the time required 

 to produce this change, and to determine whether 

 the effect was permanent, or only temporary. 

 The red tinge was found to be communicated much 

 more quickly to the bones of growing animals than 

 to those which had already attained their full size. 

 Thus the bones of a young pigeon were tinged of 

 a rose colour in twenty-four hours, and of a deep 

 scarlet in three days ; while in the adult bird, 

 fifteen days were required merely to produce the 

 rose colour. The dye was more intense in the solid 

 parts of those bones which were nearest to the 

 centre of circulation, while in bones of equal soli- 

 dity, but more remote from the heart, the tinge 

 was fainter. The bone was of a deeper dye in 

 proportion to the length of time the animal had 

 been fed upon madder. When this diet was dis- 

 continued, the colour became gradually more faint, 

 till it entirely dissappeared.t 



* Phil. Trans, for 1736, vol. xxxix. 287 and 289. It appears 

 that this effect of madder had been noticed by Antoine Mizaud, a 

 Physician in Paris, as long ago as the year 1572. 



t These experiments by no means prove, as was once supposed, 

 that the substance of the bone is renewed with every change of hue ; 



