OF NUTRITION. 271> 



457. Respecting the nature oi' this consumption, there 

 has been much dispute whether it affects the solids,* 

 or, whether, according to some very acute writers, f 

 these, when once formed and perfected, remain invari- 

 ably entire. 



458. There can be no doubt that some of the similar 

 solids, v. c. the epidermis and nails, are gradually de- 

 stroyed and renewed ; and the same is proved respect- 

 ing even the bones, by the well known experiment of 

 dyeing them with madder root, (A) and by the frequently 

 surprising attenuation of the flat bones, especially of the 

 skull, from defective nutrition in old age. % 



459. If I am not mistaken, those solid parts undergo 

 this successive change, which possess the reproductive 

 power — an extraordinary faculty, by which not only 

 the natural loss of particles, but even the accidental 

 removal of considerable parts, from external injuries, is 

 repaired and perfectly supplied, as the bones § and a 

 few other parts sufficiently demonstrate. 



460. On the other hand, I have been led by many 

 experiments to the conclusion — that this genuine re- 



* See the celebrated V. J. Bernouilli's Diss, de nntrit. Groning. 1669. 4to. 

 He estimates the continual, thbugh insensible, loss and reparation of the solids 

 so high, that the whole body may be said to be destroyed and renewed every 

 three years. 



•f* See J. Chr. Kemme, Beurtheilung cines Beweises vor die Immaterialitiit 

 der seele aits der Medicin. Halle. 1 776. 8vo. 



And his, Zweifel mid Erinnemngen wider die Lehre der Aerzte von der 

 Erndhntng der /est en Theile. Ibid. 1778. 8vo. 



\ Respecting this mutability of the bones, I have spoken at length in my 

 osteological work. ed. 2. p. 26, and elsewhere. 



§ Consult among others G. L. Koeler, E.vperimenta circa regenerationem 

 msiinn. Gotting. 1786. 8vo. 



Alex. Hcrm. Macdonald, De necrosi d rallo. Edinb. 179"J. 8vo. 



