296 BIOLOGY. [Book hi. 



anatomical elements liquefy, as the embryonaiy cells do nor- 

 mally : this is what is called ulceration. On the surface of the 

 skin and of the mucous membranes and in the glands, thousands 

 of epithelial cells incessantly detach themselves, fall, and 

 dissolve. 



Even in the weh of the deep tissues, a number of histological 

 elements disappear by simple resorption, and are either replaced 

 or not by elements of new formation. 



All that has gone before shows clearly that life is a thing 

 modifiable and variable in intensity and duration. In certain in- 

 dividuals it is prolonged two or three times beyond the average 

 life of their species. Thomas Parr was married at a hundred 

 and forty-two years, and was still fit to accomplish the act of 

 generation. He died at the age of a hundred and fifty-two ; and 

 Harvey, who made the post-mortem examination, found his 

 muscles still full and well developed, the viscera in a good state, 

 and no ossification of the cartilages.' 



A large number of examples are on record of partial rejuven- 

 escence in old men. White hair has become again black, and 

 new teeth have appeared. In other cases, with aged women, 

 the menses and the aptitude for fecundation have reappeared. 

 We have ourselves seen once, in the case of a woman more than 

 sixty, white hair replaced by black, after erysipelas of the hairy 

 scalp. 



In truth, death is a necessity to ail the organised beings of 

 our planet ; but it is not a fatality. As Oh. Eobin says,^ " No 

 scientific contradiction would hinder otu- conception of a perfect 

 equilibrium between assimilation and disassimilation indefinitely 

 repeated in all existing beings, without interrupting the con- 

 tinuity of that molecular renovation, and without a decomposition 

 of the organised substance ensuing .... The anatomical ele- 

 ment or organism, once produced, once born, may be supposed to 

 present a perfect equilibrium of indefinite duration between the 



'^ PMUSsophieal Transactions, 1669. 

 « Ch. Kobin, EUm. Anat., p. 96. 



