OSSIFICATION. 385 



pig had been fed upon the refuse of the dyeing- 

 vats, which contained a large quantity of the 

 colouring substance of madder. So curious a 

 fact naturally attracted a good deal of attention 

 among physiologists, and many experiments were 

 undertaken to ascertain the time required to pro- 

 duce 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 solidity, 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 the madder. 

 When this diet was discontinued, the colour be- 

 came gradually more faint, till it entirely dis- 

 appeared. I shall have occasion, in the sequel, 

 to discuss the inferences which have been drawn 

 from these curious facts. 



VOL. I. c c 



