3io dbforption. [Book IX. 



changing throughout life, and as all the bones lofe 

 confiderably of their weight in extreme old age. 



At the fame time, however, that their actual weight 

 is leffened, their fpecific gravity is increafed ; for the 

 bones of old people are thinner and more compact in 

 their, fides, and have larger cavities. By chemical ana- 

 lyfis, the proportion of earth is found to be increafed 

 in the progrefs of life. 



The abforbents are particularly numerous in glands, 

 and very probably have their influence in producing 

 the phenomena of fecretion. The fluids, which are 

 fecreted, for lubricating die joints and mufcles, and 

 for moiftening the feveral cavities of the body, are 

 continually renovated by the abforbents, which take 

 up what is already efFufed, while more is fupplied by 

 the arteries. 



The ufes of the glands connected with the lympha- 

 tic veflfels are not well underftood, but from their 

 being univerfal, and frorn our not being able to find 

 a fingle lymphatic veflel, which does not, in its pro- 

 grefs towards the heart, pafs through fome of them, 

 it may be concluded that their ufes are very important. 

 One of the purpoles, however, which they ferve, is, 

 probably, to impede any thing injurious, which may 

 be taken up by the abforbents, from entering thq 

 mafs of blood j and in this way the minute ramifica- 

 tions, into which the lymphatics are divided in their 

 paflage through thefe glands, may perform the office 

 of a filter. There are feveral arguments which might 

 lead us to believe, that the lymphatic glands belong- 

 ing to the lacteals have fome fhare in digeftion, or in 

 fitting the chyle for entering the mafs of circulating 

 fluids ; but their influence in this refpect is not proved., 

 nor does it feem eafy to afcertain it. Several hypo- 

 thefes have been formed by ingenious men, with a 



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