OLEAGINOUS COMPOUNDS. 73 



Blood is more constant, being comparatively little dependent upon the supply 

 directly furnished by the food ; and here, therefore, we have an additional proof 

 that the organism itself possesses the power of generating fat from other mate- 

 rials, so as to supply what may be deficient in the aliment. In its normal condi- 

 tion, the Blood contains from about 1.4 to 3.3 parts of fat in 1000 ; but this 

 proportion may undergo a large temporary increase, by the admixture of chyle 

 peculiarly rich in oily matters. Thus when blood is drawn within an hour or 

 two after a meal including much fat, particularly if this had been preceded by 

 a long fast, the admixture of chyle is indicated by the " milkiness" of the serum, 

 which is found on examination to depend upon the presence of the " molecular 

 base" of the chyle ; and the total proportion of fatty matter in the blood then 

 considerably exceeds the average. In a few hours more, however, the serum 

 recovers its usual clearness, and the excess of fat in the blood disappears ; owing, 

 it may be reasonably surmised, to its consumption in the processes of nutrition 

 and respiration. The saponifiable fatty matters proper to the blood exist in it 

 (excepting in the case just stated) only in the saponified condition; this change 

 being due to the influence of the fixed alkalies with which they are come into 

 contact. As already mentioned, they seem to be united with the Fibrin of the 

 blood with peculiar intimacy, and they constitute not less than 3 per cent, of 

 its substance ; more than 2 per cent, of fat may be obtained from the dried blood- 

 corpuscles ; whilst the dry solids of the serum do not contain above 1.8 per cent. 

 The quantity of fat in the Lymph is never large; and usually only traces of 

 this substance are found. 



42. Next to the nutrition of the adipose and nervous tissues, the most obvi- 

 ous purpose to which the Fatty matters of the chyle and blood are subservient, 

 is the maintenance of Animal Heat. The conditions of this calorifying process 

 will be more particularly considered hereafter (CHAP, xin.); and at present it 

 will be sufficient to state, that it seems essentially to consist in the union of the 

 carbon and hydrogen of fatty and other combustible matters, with oxygen intro- 

 duced by the respiratory process; thus generating carbonic acid and water, 

 which are set free through the same channel. But there is strong reason to 

 believe, that Fatty matter performs a most important part in the assimilation 

 of even the albuminous constituents of the food, and in their conversion into 

 plastic material in the first place, and subsequently into actual tissue. It has 

 been shown by Lehmann and Elsasser, that the combination of fat with protein- 

 compounds renders the latter much more easily reducible by the digestive pro- 

 cess; and it has also been shown by Lehmann, that the presence of fat is 

 necessary to enable albuminous matters to act as ferments; whence he comes 

 to the conclusion, on chemical grounds only, that "fat is one of the most active 

 agents in the metamorphosis of animal matter." This view derives support 

 from a large number of facts with which the Physiologist and Pathologist are 

 familiar. For, as was first specially noticed by Ascherson, 1 fat is always present 

 in considerable amount in newly-forming organized fabrics; it being a uni- 

 versal constituent of the nuclei of cells, both in the Vegetable and Animal 

 kingdoms, and being a large component of embryonic structures generally. 

 Moreover, as just now pointed out, the fat of the blood is most intimately as- 

 sociated, and is combined in largest amount, with the most vitalized constituents 

 of the blood, namely, the fibrin and the corpuscles; and plastic exudations 

 from the blood contain much more true fat than the non-plastic, although the 

 latter may contain a considerable amount of cholesterin. So, again, those can- 

 cerous growths whose increase is most remarkable for its rapidity, contain a 

 large amount of fat. The remarkable power which cod-liver oil has been found 



1 See his Memoir "Ueber die physiologische Bedeutung der Fettstoffe," in "Mailer's 

 Archiv." 1840. 



