FORMATION OF FAT. 



seeing that there is no other source whence 

 it can be derived, it is obvious, if we sup- 

 pose fat to be formed from albumen, fibrine, 

 or caseine, that, for every 120 equivalents 

 of carbon deposited as fat, 26 equivalents of 

 oxygen must be separated from the elements 

 of these substances ; and further, if we con- 

 ceive fat to be formed from starch, sugar, or 

 sugar of milk, that for the same amount of 

 carbon there must be separated 90, 100, and 

 110 equivalents of oxygen from these com- 

 pounds respectively. 



There is, therefore, but one way in which 

 the formation of fat in the animal body is 

 possible, and this is absolutely the same in 

 which its formation in plants takes place ; it 

 is a separation of oxygen from the elements 

 of the food. 



The carbon which we find deposited in 

 the seeds and fruits of vegetables, in the form 

 of oil and fat, was previously a constituent 

 of the atmosphere, and was absorbed by the 

 plant as carbonic acid. Its conversion into 

 fat was accomplished under the influence of 

 light, by the vital force of the vegetable ; and 

 the greater part of the oxygen of this car- 

 bonic acid was returned to the atmosphere 

 as oxygen gas.* 



In contradistinction to this phenomenon 

 ol vitality in plants, we know that the ani- 

 mal system absorbs oxygen from the atmo- 

 sphere, and that this oxygen is again given 

 out in combination with carbon or hydrogen ; 

 we know, that in the formation of carbonic 

 acid and water, the heat necessary to sus- 

 tain the constant temperature of the body is 

 produced, and that a process of oxidation is 

 the only source of animal heat. 



Whether fat be formed by the decomposi- 

 tion of fibrine and albumen, the chief con- 

 stituents of blood, or by that of starch, sugar, 

 or gum, this decomposition must be accom- 

 panied by the separation of oxygen from the 

 elements of these compounds. But this 

 oxygen is not given out in the free state, be- 

 cause it meets in the organism with sub- 

 stances possessing the property of entering 

 into combination with it. In fact, it is 

 given out in the same forms as that which 

 is absorbed from the atmosphere by the skin 

 and lungs. 



It is easy to see, from the above consider- 

 ations, that a very remarkable connexion 

 exists between the formation of fat and the 

 respiratory process. 



XVIII. The abnormal condition, which 

 causes the deposit of fat in the animal body, 

 depends, as was formerly stated, on a dis- 

 proportion between the quantity of carbon 

 in the food and that of oxygen, absorbed by 

 the skin and lungs. In the normal condi- 

 tion, the quantity of carbon given out is 

 exactly equal to that which is taken in the 

 food, and the body acquires no increase of 

 weight from the accumulation of substances 

 containing much carbon and no nitrogen. 



* See Appendix, No. 1 ), on the formation of 

 MHX and honey by the be;. . 



If we increase the supply of highly car- 

 bonized food, then the normal state can only 

 be preserved on the condition that, by exer- 

 cise and labor, the waste of the body is in- 

 creased, and the supply of oxygen aug- 

 mented in the same proportion. 



The production of fat is always a conse- 

 quence of a deficient supply of oxygen, for 

 oxygen is absolutely indispensable for the 

 dissipation of the excess of carbon in the 

 food. This excess of carbon, deposited in 

 the form of fat, is never seen in the Bedouin 

 or in the Arab of the desert, who exhibits 

 with pride to the traveller his lean, muscu- 

 lar, sinewy limbs, altogether free from fat; 

 but in prisons and jails it appears as a puf- 

 finess in the inmates, fed, as they are, on a 

 poor and scanty diet ; it appears in the se- 

 dentary females of oriental countries; and 

 finally, it is produced under the well known 

 conditions of the fattening of domestic 

 animals. 



The formation of fat depends on a defi- 

 ciency of oxygen ; but in this process, in the 

 formation of fat itself, there is opened up a 

 new source of oxygen, a new cause of ani- 

 mal heat. 



The oxygen set free in the formation of 

 fat is given out in combination with carbon 

 or hydrogen ; and whether this carbon and 

 hydrogen proceed from the substance that 

 yields the oxygen, or from other compounds, 

 still there must have been generated by this 

 formation of carbonic acid or water as much 

 heat as if an equal weight of carbon or hydro- 

 gen had been burned in air or in oxygen gas. 



If we suppose that from 2 equivalents of 

 starch 18 equivalents of oxygen are disen- 

 gaged, and that these 18 equivalents of oxy- 

 gen combine with 9 equivalents of carbon, 

 from the bile, for example, no one can doubt 

 that, in this case, exactly as much heat must 

 be developed, as if these 9 equivalents of 

 carbon had been directly burned. In this 

 form, therefore, the disengagement of heat 

 as a consequence of the formation of fat 

 would be undeniable ; and it could only be 

 considered hypothetical, on the supposition 

 that carbon and oxygen were disengaged 

 from one and the same substance, in the 

 proportions to yield carbonic acid. 



If, for example, we suppose that from 2 

 atoms of starch, C^H^O 20 , the elements of 

 9 equivalents of carbonic acid are separated, 

 there will remain a compound containing, 

 for 15 equivalents of carbon, 20 of hydrogen 

 and 2 of oxygen ; for 



= C 9 O 18 + C 15 H*O 2 . 



Or, if we assume that oxygen is separated 

 from starch in the form both of carbonic 

 acid and water, then, after subtracting the 

 elements of 6 equivalents of water and 6 of 

 carbonic acid, there would remain the com- 

 pound C 18 H 14 O 2 ; for 



C 24H2O 20 = C 6 O 12 -f- H 6 O 6 -}- C 18 H w O a . 



Assuming, then, the separation of oxygen 

 in either of these forms, it remains to be de- 

 cided whether the carbonic acid and water 



