136 GENERAL ANATOMY. 



before it is produced round the viscera. The state of maturity* 

 or the period in which the growth is terminated, is that of 

 obesity also: the latter is sometimes observable in children, 

 but very rarely. In old age, the quantity of fat is diminished, 

 chiefly under the skin : this fluid then exists, especially in the 

 interior, as about the heart, in the medullary cavities of the 

 bones, &c. 



166. The properties and functions of the fatty tissue, relate 

 only to the secretion of the fat. This secretion is not made in 

 particular glands, nor in ducts: Heister and Fanton were the 

 first to doubt the existence of these glands, of which, since the 

 error of Malpighi on this subject, many authors have spoken.* 

 The secretion of fat is a perspiratory secretion, and Rigel was 

 wrong in endeavouring to revive the theory of fatty ducts, 

 which he did, at the same time he brought forward his hypo- 

 thesis upon the use of the renal capsules: according to this 

 author, the fat which surrounds the kidneys and its pelvis, is 

 formed in these capsules, whence it is carried by particular 

 ducts, which ducts, however, he had not been able to inject. 

 Does fat directly result from the organic action of the vessels 

 which deposit it in the adipose vesicles? or, is it already formed 

 in the circulating blood? or has it a yet more remote origin? 

 M. Ev. Hornet fixes its origin in the intestine; he thinks, that 

 like the chyle, it is a product of digestion, and that it is ab- 

 sorbed by the great intestine. This opinion is based, among 

 other facts, upon the existence of the fat, or the yolk of egg, 

 in the intestine of oviparous vertebrata, in the foetal or larval 

 state, and upon some morbid facts that are not very conclusive. 



167. The fat is continually taken up by the absorbent ves- 

 sels; the action of these Vessels is demonstrated by its dimin- 

 ishing in quantity in several circumstances. This action is 

 equal to the secretion, when the quantity of fat remains the 

 same. The exhalation and absorption of the fat, is occasionally 

 very rapid, as proved by many facts. Children that have be- 

 come emaciated, in consequence of sickness, resume all their 



* De usu glandulctrum superrenalium in anim. nee non de origine adipis 

 disq. anat. philos. Hasniae, 1790, 

 f Phibsophical Transactions, ann. 1813. 



