60 



ADIPOSE TISSUE. 



Schenke, Tulpius, Morgagni, at)d others, 

 Ilewson and several coteniporary observers 

 remarked instances of opacity and milkiness 

 of the serum of the blood, and from ocular 

 inspection as well as experiment and obser- 

 vation, inferred that these appearances arose 

 from the presence of oil in the blood or its 

 serum. Soon after Dr. Gregory, in his Con- 

 spectus, or View of the Institutions of Medicine, 

 was led to infer apparently from the fact stated 

 by Ilewson, that in persons in whom the 

 serum was opaque or milky, this depends on 

 the presence of fat which is undergoing ab- 

 sorption, or resumption into the system. This 

 representation, however, was entirely conjec- 

 tural ; and no direct proof of the fact that oil 

 does exist in certain states in the venous blood 

 was given till Dr. Traill, in 1821 and 1823, 

 furnished accurate chemical evidence on the 

 point. The inferences of Dr. Traill have been 

 since confirmed by the experiments of Dr. 

 Christison, who found that milky serum con- 

 tains oleaginous or adipose matter, consisting of 

 the two adipose principles elaine and stearine.* 



The general conclusions, therefore, that may 

 be deduced from the facts now stated are that 

 in the healthy state adipose matter in small 

 proportion exists in the fibrine of the blood, 

 and in a still smaller portion in the serum ; 

 and that in certain morbid conditions of the 

 system, in which there is any process of mis- 

 nutrition or paratrophia, oily matter in con- 

 siderable quantity may be found in the blood, 

 either in consequence of absorption or non- 

 deposition. 



To account, however, for the secretion of 

 adipose matter, it is not absolutely requisite to 

 prove that oleaginous or adipose matter exists 

 in the circulating fluid. Even were it ascer- 

 tained that oil or adipose matter does not exist, 

 or cannot be detected in any of the elements 

 of healthy blood, the fact would not form a 

 stronger argument against its formation from 

 that fluid, than in the case of several other 

 principles which enter into the composition 

 of the animal tissues, and which nevertheless 

 do not exist in the blood. Thus neither gela- 

 tine, which exists abundantly in skin, tendon, 

 cartilage, ligament, and bone, ncr osmazome, 

 which is found in muscle, are contained in 

 healthy blood. But we know that the chemical 

 element of these substances exist in the blood, 

 and we farther know that gelatine consists very 

 nearly of the same chemical elements as albu- 

 men ; and we must infer, therefore, that it is 

 the faculty of the living tissues or vessels to 

 arrange these elements in that manner and 

 proportion in which they may constitute re- 

 spectively gelatine and osmazome. The same 

 reasoning may be applied to explain the for- 

 mation of fat in the adipose tissue. Its ele- 

 ments already exist in the blood, and the livino- 

 agency of the tissue seems all that is requisite 

 to effect its deposition. Its composition and 

 history would also show that it is a secreted 

 prod act which consists of superfluous chemical 



* Edin. Mcd. and Surer. Journal, vol. xxxiii. 

 p. 274. 



elements not required in the formation of the 

 albuminous and gelatinous tissues. 



On this subject the interesting experiments 

 of Berard* and Dobereinerf may, perhaps, fur- 

 nish some intelligible means of illustration. 

 The former chemist found that by mixing one 

 measure of carbonic acid, ten measures of 

 carburetted hydrogen, and twenty of hydrogen, 

 and transmitting the mixture through a red-hot 

 tube, he procured artificially several white 

 crystals which were insoluble in water, soluble 

 in alcohol, and fusible by heat into an oily 

 fluid. The latter chemist prepared a similar 

 substance from a mixture of coal-gas and aque- 

 ous vapour. 



It may therefore be inferred that while ani- 

 mal fat is chiefly a combination of bicarbonated 

 hydrogen with oxygen, or, in other words, a 

 highly carburetted hydrate of oxygen, and con- 

 tains either little or no azote, it is the animal 

 substance which makes the nearest approach 

 in chemical constitution to the vegetable prin- 

 ciples. So close, indeed, is this approxima- 

 tion that Raspail thinks it may be in this re- 

 pect compared with starch; and as the different 

 forms of fecula are prepared by the vegetable 

 tissues for the nutritious stores of the vegetable 

 during the process of development, he ob- 

 serves that, in like manner, fat is deposited 

 whenever the nutritious function is in excess 

 in the animal organs. 



It was a singular fancy of Fourcroy that 

 the deposition of fat in animal bodies was in- 

 tended as a sort of vent for the superfluous 

 and unnecessary proportion of hydrogen, since 

 the idea is at variance with chemical facts ; and 

 it is not less singular that such a hypothesis 

 should receive any countenance from Blumen- 

 bach. Carbon is the principle which predo- 

 minates most largely in fat ; and if any atten- 

 tion is to be given to such views, the adipose 

 tissue ought to be regarded as the outlet for 

 superfluous carbonaceous matter, or at least 

 carbonaceous matter in a much larger pro- 

 portion than hydrogen and oxygen. The pro- 

 per physiological view, however, of this ques- 

 tion appears to be, that as the tissues of the 

 animal body consist chiefly of carbon, hy- 

 drogen, oxygen, and azote united in variable 

 proportions, and as most of these tissues either 

 contain or seem to require azote, the adipose 

 appears to be destined to receive whatever 

 carbon, hydrogen, and oxygen, are not re- 

 quired to be united with the azote, in the forma- 

 tion of the albuminous, the gelatinous, or the 

 albumino-gelatinous tissues. 



On the mechanism of the deposition of fat 

 we possess no exact information. But various 

 facts may tend to throw some light on the cir- 

 cumstances under which it takes place, and 

 the history of the state of the adipose tissue at 

 different periods of life is instructive. 



In the foetus the adipose tissue contains a 

 sort of whitish, solid, granular matter, which 

 resembles adipocere rather than genuine fat. 



* Ann. de Chimic, 1817, t. v. p. 290. 

 t Zur Pneumatischen Phytochemie, 8vo. Jcua. 

 1822. 



